^ 578 Bashford Dean Memorial Volume 



5.1 ft. (largest 6.4 ft.) — with a correspondingly small abdomen (Text-figures 5 and 7)- 

 Yet in its right uterus it may carry as many as 7^12 large eggs and embryos. On the other 

 hand, the nurse shark is large (average adult about 8 ft. long), broad and somewhat flat, 

 and has a large abdominal cavity. Both of its uteri are functional and at breeding season 

 become enlarged into a pair of saddlebag-like organs each of which may contain as many 

 as 21 of the large eggs portrayed m Text-figure 16. The porbeagle is a fairly large shark. 

 Shann notes females from 5-9 ft. long — more of the smaller size being recorded. I have 

 no data for the size of the body cavity, but it must be large to accommodate the eggs and 

 embryos noted above. Both uteri of Laynna are functional. Three and occasionally four 

 young are produced, but one on each side, or one on one side and two on the other are 

 more common. The young at birth are probably 28-31 in. long, and, since these young 

 sharks are very large forward, they must fill the uteri and the abdominal cavity quite full. 

 But to sum up, it can be said with assurance that the evidence points to the belief that 

 in proportion to the size of its hody cavity, the frilled shark ripens and incubates the largest 

 eggs known at this writing. 



With the making of these historical notes a part of the record dealing with the size of 

 the encapsuled eggs ot Chlamydoselachus, we will now turn to the study of the formation 

 of the capsule. 



FORMATION OF THE EGG CAPSULES 

 OF CHLAMTDOSELACHUS AHD OF GIHCLTMOSTOMA 



The presence of the thick keratinoid shell about the egg of an ovoviviparous shark is 

 surely an archaic feature. As Dean long ago (1903) pointed out, this is a heritage from its 

 egg-laying ancestors. Now all egg-laying elasmobranchs known to me have on their 

 shells tendrils or holdfasts which catch on seaweed, stones, and other objects. Thus 

 anchored, shell and egg escape being rolled about and injured or covered with sand or 

 silt, and are assured of fresh water and oxygen. 



As in other sharks, so in Chlaynydoselachus these capsules are secreted by the shell 

 gland, the interior of which is shown in Text-figure 13. For a description of this gland 

 see page 550. As I have pointed out earlier, the egg shell exhibits minute striae, which 

 sometimes have a faint spiral arrangement, and which in all cases are gathered up and 

 extend out on the processes. For these see Figures 2 and 3, plate I. These striae are 

 undoubtedly impressed on the capsule during its formation. The peculiar internal 

 structure of the shell gland seen in Text-figure 13 must be responsible for these. The shell 

 gland is somewhat flattened in torm and I judge that the raphes are formed at the sides 

 where the dorsal and ventral inner surfaces of the gland are united. The structure of the 

 shell gland in Chlamydoselachus has yet to be thoroughly described and the details of its 

 function explained. 



Excepting only the round eggs portrayed by Dean, all egg capsules of the frilled 

 shark figured have a long functional process at one end of the capsule. In most of the 

 other eggs portrayed, the other end of the capsule has a low conical blunt nipple-like 



