TUNICATA 661 



ORDER 1. MULTISTIGMATEA.* 



Body barrel-shaped, with a thin tunic and with muscle bands form- 

 ing complete rings; openings lobed and at opposite ends of the body; 

 respiratory partition with 2 rows of stigmata; life history including 3 

 types of asexually produced individuals and a fourth type arising from 

 a fertilized egg: 3 genera. 



DOLIOLUM Quoy and Gaimard. Sexual generation with 8 muscle 

 bands and with 12 oral and 10 cloacal lobes; first asexual generation, 

 with 9 muscle bands and 10 oral and 12 cloacal lobes. From the hinder 

 end of this individual grow a dorsal protuberance and a ventral stolon; 

 the buds, originating on the latter, migrate to the former, which be- 

 comes long and tail-like and bears 5 rows of buds, of which the median 

 row becomes detached to form the next asexual generation. The animals 

 of this generation are similar to the sexual generation except that they 

 have no sexual organs and have a ventral stolon which produces buds 

 which become detached and grow into the sexual generation. About 13 

 species are known, mostly in the warmer oceans. 



D. denticulatum Quoy and Gaim. Sexual generation with a bent 

 respiratory partition which has about 40 stigmata on each side ; digestive 

 canal straight ; length 3 mm. : Atlantic Ocean and Mediterranean Sea. 



ORDER 2. ASTIGMATEA.f 



Body usually somewhat flattened dorsoventrally, with terminal or 

 subterminal oral and cloacal openings; tunic thick; muscle bands do 

 not form complete rings in many species; respiratory partition reduced 

 to a ciliated bar which runs diagonally from the dorsal body wall to the 

 O3sophagus in the ventral; life history including 2 types of individuals, 

 a solitary and an aggregated, which alternate with each other: 2 genera 

 and about 25 species. 



Key to the genera of Astigmatea: 



o, Nucleus usually present, when absent muscle bands numerous; salpa 



chain straight 1. SALPA 



o. No nucleus present ; salpa chain often circular 2. CYCLOSALPA 



1. SALPA Forskal. Digestive tube usually bent on itself and con- 

 tained in the nucleus; 1 to 5 embryos formed; chain double: about 18 

 species; in all the warmer seas. 



* See "Cyclomyaria et Pyrosomida," by G. Neumann, Das Tierreich, 1913. 

 t See "The Genus Salpa," by W. K. Brooks and M. M. Metcalf, Mem. Johns Hop. 

 Univ., Vol. 2, 1893. "Desmomyarla," by J. E. W. Ihle, Das Tierreich, 1912. 



