664 CHORDATA 



Marseilles and other Mediterranean cities. Over 1,200 species of ascidians 

 are known, grouped in 2 or 3 orders. 

 Key to the orders of Ascidiacea: 



Oj Sessile ascidians. 

 6i Simple ascidians, or forms loosely connected by a stolon. 



1. ASCIDIAE SIMPLICES 



6j Colonial ascidians, forming compact masses 2. Ascidiae compositae 



Cj Pelagic ascidians 3. Ascidiae luciae 



Order 1. ASCIDIAE SIMPLICES.* 



Solitary ascidians, or when colonial always loosely connected and 

 with the tunics separate and distinct, and not fused together; never free- 

 swimming: about 4 families and over 500 species. 



Key to the families of Ascidiae simplices: 



Ci Individuals not permanently joined together, 

 6i Body more or less spherical and often stalked. 



Ci Colors dull ; surface often incrusted with sand 1. Molgulidae 



c. Colors often bright, surface usually free from sand 2. Cynthiidae 



6j Body cylindrical, elongate and not stalked 3. Ascidiidae 



a. Individuals joined by creeping stolons 4, Clavelinidae 



Family 1. MOLGULIDAE. 



Body spheroidal, seldom stalked, with dull, usually gray colors and 

 often incrusted with sand or mud; mouth with 6 outer lobes and with 

 branched inner tentacles; cloaca with 4 lobes; intestine usually on the 

 left ; kidney and heart on the right side of the branchial sac ; reproductive 

 organs either paired or not, in latter case either on right or left side ; 

 animals solitary, often in sand or mud: about 14 genera and over 100 

 species. 



Key to the genera of Molgulidae here described: 



Oi Body not stalked. 



hi Branchial sac with longitudinal bars 1. Molgula 



6, No such bars. 



Ci No corkscrew-shaped infundibula on branchial sac 2. Eugyra 



c. Such infundibula present 3. Bostrichobranchus 



c. Body stalked 4. Riiizomolgula 



1. MoLGTTLA Forbes. Siphons usually long and vei-y contractile; 

 tunic thin and more or less transi)arent, although often incrusted with 

 sand and dirt; gonads paired and usually hermaphroditic; branchial sac 

 large, with 6 or 7 longitudinal folds or bars: cosmopolitan; 50 or more 

 species, some of which are not fixed, 10 American. 



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

 Proc. Bost. Soc. Nat. Hist., Vol. ;;4, 1912. 



