668 CHORDATA 



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 coiiinion 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. Perophora 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: 

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



1. BOTRYLLIDAE 



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

 6i Colony not inerusting. 



Ci Colony without common cloacal openings 2. Distomidae 



c Colony with common cloacal openings 3. Polyclinidae 



63 tolony inerusting 4. Didemnidae 



Family 1. BOTEYLLIDAE. 



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 : 



«i Individuals in circular, star-shaped, or elliptical groups 1. Botryllus 



Oa Individuals not in regularly arranged groups 2. Botrylloides 



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

 Proc. Best. See. Nat. Hist., Vol. 34, 1910. 



