1 6 University of Michigan 



them open and examined the viscera. The "uterus," or mem- 

 brane containing the young, was well developed as two long 

 sacs nearly a foot in length. Each sac was well supplied with 

 veins and arteries. After cutting a pair of these sacs open the 

 young were found folded about one another, and all moved 

 slightly. Each young shark was found furnished with a long 

 umbilicus, as long, or longer, than the length of the embryo. 

 It was attached to the walls of the sac by a placenta which 

 much resembled a clot of blood and was an inch or more 

 in diameter. The walls of the sac were elastic and of rather 

 thick membrane, also somewhat spongy in texture. The young 

 sharks would all wriggle about and finally break away. When 

 some were thrown overboard they swam slowly away, or sank 

 out of sight. All were perfectly formed and of about uniform 

 size, with characteristic dark blotches about the tips of the 

 dorsals and caudal. In size they were about 225 mm. in length. 

 One female we opened was parasitized with a number of ex- 

 ternal copepod crustaceans (Pandariis siniiatiis), which were 

 quite active, moving about over the back and fins of their host. 

 The gestation of this shark I had not noticed previously, al- 

 though I had reported* it from the observations of my friend, 

 Dr. Richard J. Phillips, at Corson's Inlet, N. J. 



The accompanying figure shows a view made from life of 

 one of the uterine sacs dissected out, with the young sharks 

 attached. 



Raja eglantcria Lacepede. — Magothy Bay and Smith Island. 



Dasyatis say (Le Sueur). — Smith Island. 



Pteroplatea micrura (Schneider). — Several caught in the 

 hauling-seine, the larger ones about 1320 mm. wide, near 

 Smith Island. 



* Science, XXX, December 3, 1909, p. 815. 



