191'] Ritter-Forsyth: Ascidiaiis of Southern California 441 



4. Styela hemicaespitosa Eitt. 



(Known in 29 fath. Hitter, 1913.) 



5. Ascidia (Phallusia) vermiformis Ritt. 



(Known in 30 fath. Ritter, 1913.) 



6. PsammapUdiiim spauhliniii Eitt. 



(Known in 33 fath. Ritter, 1913.) 



7. Trididemnum (Videmnum) opacum Ritt. 



(Known in 33 fath. Ritter, 1913.) 



Search for these seven species in the littoral zone will be among 

 the interesting motives of future ascidian collecting. 



Synoptic Descriptions of Genera 

 The following s.ynoptie description and arrangement of the genera, 

 representatives of which are treated in the paper, has been drawn up 

 primarily for the use of students, other than specialists on ascidians, 

 who may want to use the local species in more general zoological or 

 biological studies. This being the main purpose, questions of the best 

 sy.stem of classification and nomenclature, with which specialists in the 

 group are much interested at present, are considered no further than 

 to make sure that all descriptions, definitions, arrangements, and 

 names have the sanction of at least some of the most experienced 

 aseidiologists. 



Suborder I. ASCIDIAE SIMPLICES 

 Individual animals of considerable size, rarely less than 1 cm. in diameter; 

 very irregular in form but predominantly massive; sometimes semitransparent, 

 sometimes leathery in appearance, sometimes coated with sand; sedentary; often 

 firmly attached to rocks and other objects in adult life; never, as here under- 

 stood, propagating by budding. 



Genus 1. Molgula (Caesira, some authors) 



Body usually unattached boeause the animal lives on sandy or muddy bottoms, 

 but sometimes attached to rocks, occasionally pedunculated. Branchial orifice 

 6-lobed, atrial 4-lobed. 



Outer coat (test) somewhat cartilaginous, leathery or membraneous, fre- 

 quently covered with sand, which may be attached to hairlike processes or 

 embedded in the surface layer. 



Branchial tentacles always compound. 



Branchial sac with well-developed folds, usually from five to seven on each 

 side; the branchial slits (stigmata) almost always curved, or even developed 

 into spirals and arranged in pockets or ampullae in the branchial folds. 



Intestine always on the left side. 



Sexual organs usually on both sides but not infrequently on one side only; 

 when so, almost always on the left. Ovary and testis more or less intimately 

 associated. 



Excretory organ on the right side only, with the exception of one genus, 

 JRhizomoloula, in which it is on the left side. 



