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APPENDICES.

of equal size and there is no reason to doubt that in each case they were the product of one pairing. In two cases (June, 1905, and 9th August, 1896) there is a well- marked difference in the size of each of the twins; in one case, the smaller twin appears to have been paired for twenty-nine days after the pairing for the larger foetus, and in the other case the interval between the two pairings appears to have been twenty-eight days. Captain Bull has recorded* (in Collett) a most remarkable case from Iceland; a finner, captured on 10th July, 1909, contained no fewer than six foetuses, of which three were 888 mm. long each, while the length of the remain- ing three varied between 444 and 522 mm., their average length being 478 mm. this case I see reason for believing that the three large foetuses were the product of one pairing and that the three smaller foetuses were the product of a later pairing; the interval between the two pairings appears to have been about twenty days.

In

In endeavouring to interpret these cases reference may be made to Major Barrett-Hamilton's notes on the genitalia of the female finners Nos. 50, 65, 195, 207, and 287, as set out above; these notes appear to warrant the belief that occasionally at all events both ovaries may be functional in these whales at one and the same time. No. 15, a finner, pregnant with a male fœtus 1,385 mm. long, and in which the orifice of the vagina was remarkably swollen externally (a condition which sug- gested "heat"), can hardly be prayed in aid, because Major Barrett-Hamilton tells us that the ovary in connexion with the unused uterine cornu was small, apparently without corpora lutea, and with no perceptible duct; and because 1,385 mm. is far more than the greatest difference of length which has been recorded as subsisting between twinned fœtuses.

I am inclined to think that where the twins are of equal size the two ova have been shed by one ovary and fertilized at one pairing; Captain Bull's case indicates to my mind that occasionally three ova may be shed simultaneously by one ovary. Those cases in which the twins are of unequal size may, I think, be regarded more probably as instances of superfotation than as instances of true twinning. In such cases the smaller fœtus may be explained, in my opinion, by assuming that both ovaries of the dam were functional; that at a normal interval after the estrus which resulted in the pairing for the larger fœtus a further astrus was induced by the con- tinued activity of the second and previously unused ovary; during this further cestrus, supposing the development of the earlier embryo to be too little advanced to obstruct the passage to the unoccupied uterine cornu, an ovum from the second ovary was fertilized. Captain Bull's case appears to me to show further that in those cases where one ovary is capable of shedding twinned or triplicated ova the other ovary may possess a corresponding fertility which may assert itself in the event of superfœtation.

As stated above, Professor Guldberg was of opinion that finner cows do not normally give birth to young in every year, and I think that on the whole the evidence is in favour of this view. A few cases are, however, recorded from the North Atlantic in which nursing females have been found to be pregnant. Thus Professor Collett mentions a female captured on 14th August, 1896, which, being followed by her calf and having milk in her glands, was found to contain twin foetuses; he also says that in the beginning of August, 1893, two females which were followed by sucking calves were taken and found to be each pregnant with a foetus of about 2 ft. long. Mr. Haldane (Ann. Scott, Nat. Hist., 1906) mentions a female taken at Shet land which contained a fœtus 4 ft. long, and which was in milk; he expresses the The evidence opinion that this milk "must have belonged to a calf nearly weaned." as to the relation of pregnancy and lactation collected at South Georgia by Major Barrett-Hamilton may be digested as follows:-

(a) No milk present:-

Foetuses found in Nos. 282, 277, 278, 119, 45, 39, 236, 60, 73, 18, 61, 219,

237, 46, 64, 264, 270, 15, 56, 33, 254, 67, and 76-23 cases. Foetuses must have been present in Nos. 66 and 65=2 cases.

Foetus, if present, must have been large in No. 261.

At least no big fœtus present in No. 262.

Impregnation récent or probable in Nos. 50, 207, 284, and 37=4.

This case is also mentioned by Haldane, Ann. Scolt. Nat. Hist., 1910, p. 117, and by Harvic Brown, Zoologist, ser. 4, vol. 14, p. 241.

+ Both ovaries were functional in No. 39 (see footnote to p. 112 above and Appendix 1, p. 179, below).

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Calf recently weaned, impregnation either not yet or recent in No. 38. Doubtfully pregnant:-No. 185.

Virgin-but probably about to breed :-No. 79.

(b) Milk present:—

Breeding or recently impregnated; some milk present in glands :-Nos. 287

and 195 or 197.

Suckling but no note as to pregnancy :-No. 224.

Foetus found-but no note as to milk :-No. 47.

In considering this evidence from South Georgia it is, of course, necessary to bear in mind the Whaling Regulation (South Georgia) No. 1, dated the 28th July, 1913, whereby, in pursuance of the powers in him vested by Section 8 of the "Whale Fishery Ordinance, 1908," His Excellency the Governor of the Falkland Islands has ordered that: "No leaseholder shall kill or shoot any whale calf, or any female whale which is accompanied by a calf." In view of this Regulation all that can be said of the facts digested above is that so far as they go they do not conflict with the view that the calf is normally weaned either before or shortly after the reimpreg- nation of the dam.

Different statements have been made by different writers as to the relative numbers of the male and female finners; these statements may be summarized as follows:-

Cows are equal in number to bulls (Southwell).

Cows were fewer than bulls at Shetland and Hebrides-in all years except 1906 (Haldane); at Belmullet, Ireland (Burfield; J. E. Hamilton); at Leith Harbour, South Georgia, between November, 1913, and January, 1914 (Major Barrett-Hamilton).

Cows were more numerous than bulls at Newfoundland (True); and perhaps at Finmark (Mr. Cocks's records deal with 150 females and 134 males); at Shetland and the Hebrides in the year 1906 (Haldane). Mr. Burfield said that the greater timidity of the female appears to be the only explanation of the relatively smaller numbers caught in European waters; personally I am inclined to regard such discrepancies as being merely the effects of those local and seasonal changes which migration appears to induce in the constitution of the herds. Professor Collett and Mr. Haldane agree that when large numbers of fœtuses from the North Atlantic are examined the sexes appear to be about evenly distributed. At South Georgia of 24 foetuses examined 14 were females and 10 were males the total number examined is too few in either species to yield reliable proportional numbers, but the preponderance of female foetuses appears to be much less marked than in the case of the southern humpback foetuses.

If in reality females are not very largely in excess of males among finners, and if in reality they are very considerably in excess of males among humpbacks, we may eventually recognize in such a difference the cause of both the longer sexual season and the occasionally markedly greater fecundity which appear to characterize the finner cow as compared with the female humpback.

Attention may be called in passing to a point which may turn out to be of importance later on. Taking the specimens examined for pregnancy at South Georgia by Major Barrett-Hamilton as a fair sample of the whole catch, it would appear that there, between mid-November and mid-January, 92 per cent. of the mature females are pregnant; it is, of course, necessary to bear in mind again the local Whaling Regulation No. 1 of the 28th July, 1913, which has been cited above. Now both Collett and Mörch say that in Norwegian waters only about one-fifth of all the female finners caught are pregnant, and Mörch adds that "a lesser number will be accompanied by calves." Making allowance for the absence of nursing and immature females from the South Georgia catch, the proportion of pregnant females seems to be too low in Norwegian waters; perhaps this difference is not a real one, but only a result of those difficulties which have prevented the whalers from making such nice observations in the past.

As already mentioned, the young are believed to be about 20 ft. long at birth. The smallest known specimen appears to be one mentioned by Pouchet; this was 5,300 mm. long, and was killed on 28th November, 1884, near St. Tropez, on the Mediterranean coast. Although Pouchet thought it to be a weaned calf it is obvious, as Guldberg pointed out, that the specimen was newly born. Guldberg mentions three calves, whose lengths are given as 6,250, 5,750-6,000, and 7,000 mm., which were taken with their mothers at Vardö in April and June, 1884. Mr. Haldane speaks of a fœtus of 22 ft. and others of 20 ft. at the Shetland stations.