668 CHOEDATA 



FAMILY 4. CLAVELINIDAE: 



Body elongated and joined by means of creeping stolons with other 

 individuals, forming thus a branched colony with a common blood 

 system, or rarely embedded in a common gelatinous tunic; apertures 

 simple, rarely lobed: about 8 genera and 28 species. 



1. CLAVELINA Savigny. Zooids elongate, made up of 2 regions, a 

 thorax and an abdomen, joined by stolons with one another; apertures 

 simple: about 8 species. 



C. oblonga Herdman. Zooids club-shaped, 30 mm. long or less; 

 tunic thick and transparent; branchial sac with about 15 rows of stig- 

 mata ; tentacles about 20 in number, short and stout : Bermuda ; common. 



2. PEROFHOBA Lister. Body compact and not composed of 2 re- 

 gions, the intestine being at the side of the branchial sac ; both apertures 

 six-lobed. 



P. viridis Verrill. Body small, oval, 3 mm. long, greenish or yel- 

 lowish in color : Vineyard Sound ; common ; often covering piles, seaweed, 

 or stones near low-water mark. 



ORDER 2. ASCIDIAE COMPOSITAE.* 



Composite, colonial ascidians, the members of a colony being joined 

 by a common tunic and often possessing a common cloaca, and arising 

 from one another by a process of budding; individuals often elongate 

 and consisting of 2 or 3 distinct divisions, called thorax, abdomen, and 

 post-abdomen (Fig. 1,014) : about 7 families. 



Key to the families of Ascidiae compositae here described: 

 <! Body without division into thorax and abdomen ; mouth not lobed. 



1. BOTBYLLIDAE 



o. Body composed of 2 or 3 divisions ; mouth with usually 6 lobes. 

 &! Colony not mcrusting. 



<?! Colony without common cloacal openings 2. DISTOMIDAE 



c Colony with common cloacal openings 3. POLYCLINIDAK 



fe a Colony incrusting 4. DIDEMNIDAE 



FAMILY 1. BOTRYLLIDAE. 



Colony either thin and crust-like or thick and fleshy, consisting of 

 individuals in groups, each group with a common cloaca; no division 

 into thorax and abdomen; branchial sac without longitudinal folds, 

 usually with 3 inner longitudinal bars; male and female gonads sep- 

 arate, on both sides of body: 5 genera with about 80 species. 



Key to the genera of Botryllidae here described: 



! Individuals in circular, star-shaped, or elliptical groups 1. BOTBYLLUB 



c, Individuals not in regularly arranged groups 2. BOTBYLLOIDES 



See "Compound Ascidians of the Coast of New England," etc., by W. Van Name, 

 Proc. Bost. Soc. Nat. Hist., Vol. 34, 1910. 



