^30 Apjpendiceii to Fourth Annual Report 



probability viviparous. The cloaca is divided into two compartments, an 

 upper and a lower. Viewed from the ventral aspect, the upper has only 

 the rectum opening into it, while the lower has the two oviducts, one on 

 either side, and a little behind, the urinary papilla, which has at its summit 

 the common opening of the two ureters. Two abdominal pores open just 

 beyond the posterior margin of the cloaca. 



The heart was enclosed in a strong pericardium and was of the ordi- 

 nary elasmobranch type. The sinus venosus was inside the pericardium. 

 The bulbus arteriosus was of similar construction to the ventricle, on 

 which account Gegenbaur describes it as an elongated, and to some extent 

 independent, segment of the ventricle, homologous with the conus arteri- 

 osus in the higher vertebrates rather than with the bulbus of osseous 

 fishes. On cutting it open longitudinally, it was seen to have four 

 rows of valves and a single representative of a fifth row. All the valves 

 ■were attached to the muscular wall by cordse tendinese. Four afferent 

 vessels spring from the ventral aorta on each side, the most anterior 

 pair dividing into two. This arrangement is similar to what I have 

 seen in other sharks, the only difference being that in this case the first 

 two pairs of vessels have their origins close to one another, whereas in 

 others, Galeus for instance, the intervals between the vessels are more 

 regular. 



The two posterior cardinals run parallel and on either side of the back 

 bone, and on reaching the anterior end of the abdominal cavity, become en- 

 veloped in a common covering ; they are still separated, however, by a more 

 or less porous septum. Each then dilates into a large hepatic sinus, so 

 that the blood entering from the liver cannot pass into either sinus of 

 Cuvier, as it can in the skate for instance ; but, practically, is compelled 

 to pass either to the right or left according as it has come from the right 

 or left lobe of the liver. The size and arrangement of these hepatic sinuses 

 no doubt corresponds to the extent of the liver. 



The brain of this, as of many other sharks, lies in a cavity very much 

 too large for it. It was itself small, and closely resembled, both in struc- 

 ture and size, that of a good sized skate. The cranial cavity proper 

 was 9^ inches long, i.e., not including the wide branches which passed 

 off to the olfactory region or the large tube in which the anterior portion 

 of the spinal cord lay. Immediately above the cerebral lobes the cavity 

 was deepest, being 2f inches, and about an inch further forward attained 

 its greatest breadth of 2 J inches. The walls and roof of the cavity had a 

 gently undulating surface, and were lined by what appeared to be a rec- 

 ticulated vascular membrane. The cartilage of the brain-box was exceed- 

 ingly thick in the regions of the auditory and nasal capsules, but above 

 the cranial cavity, measured only about an inch and a half. The olfactory 

 bulbs, eyes, and ears were all large and well developed. 



The skeleton was entirely cartilaginous, no trace of ossification being 

 found either in the head, jaws, or backbone. A longitudinal section 

 of the latter taken about the middle of the animal showed only 

 slender strips of cartilage segmenting off the notocord, the strips 

 occurring about six inches from one another. Tracing it backwards 

 towards the tail, the strips became thicker and the amount of noto- 

 cord in each segment smaller, until in the caudal fin- they were in 

 about equal proportions. All the cartilage was very soft and flexible, 

 so much so, that even several days after death the whole body could 

 be bent freely in all directions. The muscles of the trunk are of a 

 peculiar creamy-white colour and soft, though of great thickness along 

 the back. The young Greenland shark is of a dull slate colour and 

 there are a num,ber of small white spots distributed in an irregular manner 



