148 Transactions of the Canadian Institute. [vol. ix 



ing rudimentary tentacles and very short gonads. The spines of the 

 test are somewhat similar to those described by Hartmeyer for sub- 

 arctic European specimens, but in this case we have large individuals 

 with spines of this character. 



Ascidia hirsuta Agassiz appears to be the only name that has been 

 given primarily to Eastern North American specimens and is, therefore, 

 the valid one for this species. 



Specimens of large size were obtained at low tide near the station. 

 It occurs generally distributed as shown by the dredgings. 



Tethyum pyriforme (Rathke) subsp. americanum nov. 



Syn. — Cynthia {seu Halocynthia) pyriformis and. americ. 



In contrast with the great constancy in the number of the gonads 

 in the Mediterranean 7". papillosum and in the Pacific T. aurantium, the 

 number in T. pyriforme of Arctic and European seas is stated to vary 

 from 4 to 6 on the right side and to be constantly 4 on the left. An ex- 

 amination of a series of individuals from St. Andrews, shows a variation 

 of from 3 to 10 on the right side and from 5 to 14 on the left, the number 

 on the left being usually greater than that on the right. It seems best 

 to consider this as a subspecies of the Arctic T. pyriforme. 



