CLASSmCATION OF THE TFNICA.TA. 629 



The genera * in this family (which I use in the restricted sense, 

 as not including Diplosomidse and Coelocormidse) may be dis- 

 tinguished as follows : — 



("Colony thick and fleshy 1 



\ Colony thin, incrusting 2 



-. r Three rows of stigmata Didemnum. 



[ Four rows of stigmata Didemnoides. 



.-, r Four rows of stigmata Leptoclinum. 



\ Six rows of stigmata Euccelium. 



DiDEMNTJM t, Savigny, 1816. 



Colony usually thick and fleshy, rarely thin and incrusting. 



Ascidiozooids with the atrial aperture on the dorsal edge of the 

 thorax, often placed far back. Atrial siphon lobed or simple. 

 No atrial languet present. Branchial aperture 6-lobed. 



Test gelatinous or cartilaginous, usually not very hard or stiff. 

 Stellate calcareous spicules are usually present. 



Branchial sac with three rows of stigmata. 



Tentacles eight in number. 



The species may be distinguished as follows : — 



/ Test containing spicules 1 



\ Test with no spicules 2 



(Surface deeply cut up by corrugated sulci. 

 B. tortuosuin, v. Dr. (Med.) 

 Surface not cut up 3 



o r Colour yellow, with dark-brown spots. B. inarmatum, v. Dr. (Med.) 

 I Colour dull grey Z>. merme, Herdm. (N. Atl.) 



{Branchial sac prolonged beyond third row of stigmata. 

 B. graphicum, Lah. (Med.) 

 Branchial sac not prolonged 4 



f Colony white, vas deferens takes 8 turns. 

 4 -^ B. niveum, Giard. (N.W. Eur.) 



[ Colony not white 5 



P- f Colour yellow to brown 6 



I Colour blue or greenish or dark grey 7 



o f Colour rich dark brown B. Savignii, Herdm. (? S. Atl.) 



\ Colour yellow and orange 8 



[ Colour bright yellow, vas deferens takes 12 turns. [Med.) 



8 \ B. cereum \, Giard. (N.W. Eur., 



[ Colour orange B. aurantiacuTti, Herdm. ( Austr.) 



* Lissoclinum, Verrill, containing two species {L. aureum and L. tencnim) 

 from the east coast of N. America, is not sufficiently described. It will pro- 

 bably come under Leptoclinum. 



t Including Trididemnum of Delia Valle. 



\ According to Lahille, B. sargassicola, Giard (with several varieties), is a 

 variety of this species. 



