DESCRIPTION OF SPECIES 



i'5 



Table 33 



Styela paessleri Michaelsen (Text-fig. 35D-F) 

 Styela paessleri Michaelsen, 1898, p. 368. 



Occurrence. St. 53: Falkland Islands, 0-2 m. St. WS 841 : Patagonian Shelf, no- 121 m. 



External appearance. The largest specimen in this collection is 4-0 cm. high and 2-2 cm. wide, and 

 the smallest one 2-5 by 1-4 cm. The body is irregular, varying from dome-shaped to tall and columnar, 

 with the siphons close together at the upper end. The test is wrinkled, leathery and generally some 

 shade of brown. 



Tentacles. The oral tentacles are numerous, and I have counted thirty-five and fifty-eight respec- 

 tively in two specimens of moderate size; Michaelsen (1898) noted about sixty tentacles. 



Dorsal tubercle. In two specimens examined the dorsal tubercle was C-shaped with the open 

 interval posterior, and in a third specimen it was in the form of a horizontal S. According to 

 Michaelsen the opening is either a straight slit or a slit with the left end turned back. 



Gonads (Text-fig. 35D-F). The gonads are very characteristic in this species. There are two on 

 each side, each consisting of a branched ovary (ov.) and many round or pear-shaped testis follicles (t) 

 grouped round the ends of the ovarian branches. The gonads are of the Styela type, in which the 

 testis follicles are separate from the ovary instead of being closely united to it within a common 

 membrane as in Cnemidocarpa. When fully developed the testis follicles of S. paessleri may become 

 closely crowded together to form large irregular masses pressed against the sides of the ovary and to 

 some extent overlapping it. In this way the basic structure of the gonads is to some extent obscured. 



Remarks. Kott (1954) records the species from Kerguelen but is a little doubtful about the 

 identification. 



Van Name (1945) considered that S. paessleri probably includes Michaelsen's species S. pfejferi, 

 but as I have pointed out (see p. 100) the latter species is clearly distinguished by its gonads and is in 

 fact a Cnemidocarpa. 



Distribution. Subantarctic (Falkland Islands to Tierra del Fuego; PKerguelen). 



Styela partita (Stimpson) (Text-fig. 44) 

 Cynthia partita Stimpson, 1852, p. 231. 

 For synonymy see van Name 1945, p. 290, and Tokioka, 1953, p. 262. 



Occurrence. St. 2 : Ascension Island, o m. 



External appearance. The larger of the two specimens has a height of i-i cm. and a greatest width 



15-2 



