STRUCTURE OF HOOKER'S SEA-LION. 377 



0. hookeri, that in O.jubata the stomach is larger in proportion to the length of the body 

 than in either of the other species ; although naturally there was not an absolute 

 agreement between 0. gillespii and 0. hookerii in the proportions of this viscus, the 

 difference was markedly less than between either of these species and 0. jubata. The 

 spleen of 0. hookeri was 1 6 inches in length ; its breadth varies from 2-3^ inches ; the 

 greater part of the organ was of the greater breadth. So far as I can gather from 

 Mr. Forbes's description, the spleen of 0. gillepsii is nearly of the same shape, but is 

 proportionately smaller in size. In both these species there is no " beak-like pi'ocess," 

 such as that which Dr. Murie describes and figures in O.jubata. 



Neither Dr. Murie nor Mr. Forbes refers to the attachment of the omentum of the 

 spleen ; this is peculiar, and is closely paralleled in the case of the Ehinoceros, where 

 it has been lately described by Mr. Treves and myself 1 . It probably occurs in other 

 animals. The splenic omentum, instead of being attached to the spleen along the 

 middle line, is attached along two parallel lines. 



With regard to the liver, this organ presents a general agreement with the liver in 

 the other species of Sea-Lions, being characterized, as they are, by the breaking up of 

 the lobes into a very large number of lobules. The right lateral lobe is rather more 

 lobulated than in Dr. Murie's figure of that of 0. jubata ; the left lateral lobe is perhaps 

 less so, inasmuch as the furrows which break it up into lobules are nearly confined to the 

 base of the lobe ; the left central lobe (that marked V in Murie's figure) is also rather 

 less lobulated. I do not know that very much weight can be attached to such small 

 differences as are here recorded ; still in these mmute points of difference 0. hookeri 

 comes nearer to 0. gillespii, where, as Mr. Forbes has said, " the liver .... differs 

 chiefly (from that of O.jubata) in the more regular outlines of its lobes, and the much 

 smaller development of additional sulci on its inferior aspect, in these respects more 

 resembling the liver of ordinary Mammalia, and presenting less approximation to the 

 greatly complicated liver of the Seals." 



A description of the lungs of 0. hookeri would be a mere repetition of the descrip- 

 tions given by Murie and Forbes. I may mention, however, that the " lobus impar " 

 belongs to the right lung, as Murie states to be the case in O.jubata. Forbes refers to 

 the presence of the "lobus impar" in 0. gillespii, but neglects to say what relation it 

 bears to the right and left lungs. 



The heart of 0. hookeri agrees with that of 0. gillespii in the origin of the great 

 arterial trunks ; that is to say, an innominate artery gives off both carotids and one 

 subclavian ; the left subclavian takes its origin independently from the arch of the 

 aorta. In O.jubata the left carotid, as well as the left subclavian, arise separately 

 from the aorta, while the innominate gives rise to the right subclavian and right 

 carotid. 



1 Trans. Zool. Soc. vol. xii. pt. 6. 



