CLASSinCATTON' OF THE TITNTCA.TA. 



607 



B. Schlosseri (Pallas), Sav. (N.W. Eur., Med.) Yellow with rust-red dots. 

 £. Baeri, Grube. (Med.) Colony very tbin. 



J5. saww/o, Delia Valle. (Med.) Colony think ; violet -blue markings. 

 B. aurolineatus, Giard. (N.W. Eur., Med.) Yellow lines, 8 tent., asc. 



2'2 mm. long. 

 B. morio, G-iard. (N.W. Eur., Med.) Nearly black. 

 B. gemmeus, Sav. (N.W. Eur., Med.) Violet and yellow. 

 B. violaceus, H. M.-Edw. (N.W. Eur., Med.) Elue, with white lines. 

 B. tenuis, Delia Valle. (Med.) Tentacles 1-3, vessels blue. 

 B. minutus, Sav. (N.W. Eur., Med.) Asc. 1 mm., 3-5 in syst. 

 B. smaragdus,M..-'EdiW. (N.W.Eur.) Green. 

 B.pruinosus, Giard. (N.W. Eur.) Green. 



B. tapetum, Delia Valle. (Med.) Grey, 3-8 in syst., 3 tentacles. 

 B. calendula, Giard. (N.W. Eur.) Yellow, ascidiozooids 1 mm. 

 B. marionis, Giard. (N.W. Eur.) Ascidiozooids 2'5 mm., 8-10 in syst. ; 



colour brown with white and carmine. 

 B. rubigo, Giard. (N.W. Eur.) Brown, with red marks. 

 B. nibens, Aid. & Hanc. (N.W. Eur.) Yellow and red, thin test. 

 B. virescens, Aid. & Hanc. (N.W. Eur.) Greenish. 

 B. castaneus, Aid. & Hanc. (N.W. Eur.) Purple-brown, test very thiu. 

 B. Gouldii, Verr. (E. N. Am.) 

 B. bivittatus, M.-Edw. (N.W. Eur.) 



PoLTCTCLUS, LamarcTc, 1816. 



Colony tlnck and fleshy, convex on surface, often lobed. 



Systems circular or stellate in outline. 



Ascidiozooids ovate, Avith the apertures rather distant from one 

 another. 



Test gelatinous, but solid and much thickened, vessels present. 



Branchial sac large and well developed. 



Tentacles from 2 to 16 in number. 



Alimentary canal placed alongside the posterior end of the 

 branchial sac. 



Gonads placed on both sides of the body near the posterior end. 



Leaving out a few doubtful forms and older species with im- 

 perfect descriptions and which cannot now be determined with 

 any certainty, the genus contains five species. These may be 

 distinguished as follows : — 



/Ascidiozooids at least 3 mm. long 1 



[Ascidiozooids not 3 mm. long 2 



, /With 2 tentacles, placed laterally P. cyaneus, \. Dr. (Med.) 



I With more than 2 tentacles 3 



( Ascidiozooids at least 4 mm. long 4 - 



3-^ Ascidiozooids about 3 mm. long. Tentacles 8, 2 large lateral and 6 

 [ small P. violaceuSjY. Dr. (Med.) 



