562 PROF. w. A. herdman's revised 



The Order Ascidiacea is divided into three Sections — the 

 AscidisB Simplices, the Ascidise Compositse, and the Ascidise 

 Lucise. 



Suborder I. ASCIDIJ^ SIMPLIOUS, Savigny, 1816. 



This group contains fixed (rarely unattached, but never free- 

 swimming) Ascidians which are solitary, and very rarely repro- 

 duce by gemmation ; if colonies are formed, the members of the 

 colony are not buried in a common investing mass, but each 

 has a distinct test of its own. 



The Ascidise Simplices include four families — the MolgulidaB, 

 the Cynthiidae, the Ascidiidse, and the Clavelinidse. 



Family I. MOLGULID^, Lac.-Buth., 1877. 



Bodi/ usually free, sometimes fixed, rarely pedunculated. 



Test cartilaginous, coriaceous, or membranous, usually covered 

 with sand &c., which adheres to long hair-like processes of the 

 test. Branchial aperture 6-lobed, atrial aperture 4-lobed. 



Branchial sac usually loTigitudinally folded (5 to 7 folds on 

 each side) .: internal longitudinal bars not papillated ; stigmata 

 more or less curved, usuall}^ arranged in spirals. 



Tentacles always compound, usually much branched. 



Intestine attached to tlie inner surface of the mantle on the 

 left side. 



Renal sac pi'esent, upon the right side of the bod3^ 



Gonads on the inner surface of tlie mantle, usually deve- 

 loped on both sides. Larvae usually tailed, in a few species 

 anurous. 



This is the most highly differentiated family of the Ascidiae 

 Simplices. It contains the following genera : — 



/Branchial sac with no folds 1 



\ Branchial sac with from 6 to 7 longitudinal folds on each side 2 



(A pair of gonads, one on each side, the left one anterior to the intes- 

 tine...., Paxamolgula. 

 A single gonad, alongside intestine 3 



(Infundibula large, conical, placed in longitudinal rows, one in each 

 mesh Eug37ra. 

 Infundibula relatively small, corkscrew-like, many in each mesh. 

 Bostrichobranchus. 



