578 PEOI'. "W. A. HEEDMAlSr's EETISBD 



FoEBESELLA, n. gen. 



Body attached, depressed. 



Test firm, modified to form scales or plates. 



Branchial sac with only 4 folds on each side, or even only 3 on 

 the left side. 



Tentacles compound. 



This genus is formed for the reception of the remarkable little 

 " Cynthia tessellaia " of E. Forbes, which differs from all other 

 known Cjnthiinae and agrees with the Styelinae (from which again it 

 differs in having compound tentacles) in having not more than 4 

 folds on each side of the branchial sac. The " Cynthia limacina " 

 of Torbes is either the same species or very closely related to it, 

 and probably therefore comes also into this genus. 



Tlie single sufficiently known species is then 



Forhesella tessellata, Forb. (N.W. Eur.) 



Subfamily Sttelus"^, Herdman, 1881. 



Body attached, sessile, rarely incrusted with sand. Branchial 

 and atrial apertures either 4-lobed or irregular. 



Test usually coriaceous, rarely cartilaginous. 



Branchial sac with at most four folds upon each side. 



Tentacles simple, unbranched. 



Alimentary ca?2aZwith a well-marked stomach and no distinct 

 glandular csecum or " liver." 



Gonads iu the form of one or a few elongated tubes, or a 

 large number of small scattered masses (" polycarps ") attached 

 to the inner surface of the mantle. 



This subfamily includes 8 genera*, which may be distinguished 

 as follows : — 



Branchial sac absent t Styeloides. 



Bi'anchial sac present 1 



1 /Branchial sac with no folds Pelonaia. 



\ Branchial sac with folds 2 



9 r Branchial sae with no stigmata in the meshes Bathyoncus. 



'^ \ Branchial sac with stigmata in the meshes 3 



o r With only a single fold in the branchial sac Styelopsis. 



\ With more than one fold in the branchial sac 4 



* ^^tZerm, proposed by Lahille in .1887, cannot be conveniently separated 

 from Styela. 



t This is such an exceptional and remai-kable case that I cannot help suspect- 

 ing that the single specimen examined by Sluiter was merely an individual 

 abnormality. 



