BELMULLET WHALING STATION. 143 
a thrombus, which may in the course of time become organised.’ 
The organisation takes the form of a proliferation of the fibrous tissue 
of the blood-vessel wall, which in the course of time entirely replaces 
the thrombus. This tissue may be supplied with blood-vessels. 
Thrombi may become calcified, and the deposition of calcium salts 
is one of the striking features of the structures under consideration. 
Again, metazoan parasites have been known to cause thrombi,’* and 
in the cases before us it is highly probable that the nematodes have 
produced vascular lesion, or the mere presence of the eggs may have 
been sufficient to excite coagulation of the blood. From either of 
these causes the thrombi may have been formed, becoming subse- 
quently organised. It is interesting to note in this connection that 
pedunculated, if not digitated, thrombi have occurred in the human 
subject. The thrombus in Megaptera appears to have actually enclosed 
the worms which caused it, and they have been retained by the 
subsequent organisation. 
VIII.—F eiuses. 
B. musculus.—None of the foetuses examined by us were sutti- 
ciently small to be of use for embryological purposes. They were all 
perfectly formed, and even in the smallest (3 ft. 11 in.) the ventral 
furrows of the adult were represented by mere lines. 
Table VI. contains a list of the foetuses, and a detailed list of 
measurements will be found in Table XII. It may be noted that 
the 8 ft. foetus of No. 80 was mutilated by some of the workers 
before we arrived on the scene, while that of No. 31 was destroyed 
before the female was opened, apparently by the harpoon explosion. 
The sizes of both of these are therefore estimates only. The fcetus 
of No. 47 (9 ft. 4 in.) was in a hopeless state of decomposition, and 
very few measurements could be taken upon it. 
(a) Body form.—In all the fcetuses which we saw the form was 
_the same as in the adult, but in the smallest it was noticeably more 
robust. 
(b) Colouration.—This character does not differ from that of the 
adult animals. The dark tint is found in the same situations. The 
smaller foetuses are very much less pigmented. In the 3 ft. 11 in. 
foetus the whole skin was gorged with blood, and the black colour 
was confined to the following localities: back, tip of dorsal fin, tip 
of flippers, tips of flukes, tip of rostrum, and symphysis. 
B. sibbaldii.—One specimen, 7 ft. 7 in. in length, was seen. The 
upper surface was pale grey, the distal part of the dorsal fin and 
the external mouth parts were stained with black. 
IX.—Breeding Season of the Balenopterids. 
A factor which may be used in attempting to ascertain the probable 
breeding season of the large whales is the sizes of the foetuses observed 
at different times. Leaving for this purpose the Blue Whale out of 
** Macfarlane, Text Book of Pathology, 1904 ed. . 107-8. Green, Manual 
of Pathology, 1th ed., p. pe ii sii : 
“* Green, op. cit., p. 389. 
