140 BRITISH TUXICATA. 



them, and the branchial tubercle is large with the loop 

 placed transversely opening towards the ventral margin : 

 the extremities are turned forwards and backwards. 

 The oral lamina is wide, with distant ribs or pectina- 

 tions on the right side, the other side seems to be 

 smooth, though the pectinations shine through. The 

 longitudinal bars are rather delicate, and are much 

 elevated above the general surface ; the membrane 

 beneath is narrow, and there is one bar to each plication. 

 The papillary membrane is ample and has the free 

 margin much thickened and arched, and, projecting a 

 little in front of the bar, assumes the form of a short 

 obtuse papilla. 



The ovary is a large dendritic organ spread over the 

 left side of the visceral mass, the branches being stout 

 and radiating : the testis is composed of a vast number 

 of minute casca which appear on both sides of the 

 alimentary tube. 



27. Ascidia elliptica Alder & Hancock. 

 (PI. XVI, figs. 4-7; PI. XVIII, fig. 11.) 



Asc'nlia i>rintnin [JAMESON in Mem. Wernerian Soc. I 

 (1811), p. 557: PENNANT Brit. Zool. IV (1812), p. 100; 

 STEWART El em. Nat. Hist. I (1817), p. 391; COLDSTREAM 

 in Edinb. new Philos. Jonrn. XIV (1830), p. -239: THOMP- 

 SON in Ann. Nat. Hist. (1) V (1840), p. 94;] FORBES and 

 HANLKY Brit. Moll. I [1848], p. 34; [NORMAN Zoologist, 

 V (1857), p. 5708]. 



Pin- n prunum FLEMING Brit. Aniin. [1828], p. 468. 



i^Jqitlca ALDER and HANCOCK in Trans. Tyneside 

 N.F. Club, I [1848], p. 201; FORBES and HANLEY Brit. 

 Moll. II [1849], p. 374; [NOKMAX in Rep. Brit. Assoc. 

 1868 (1869), p. 302]. 



i prunum ''. THOMPSON Nat. Hist. Ireland, IV [1850], 

 p. 359. 



[Noii A$ci<l/ri j >ni n inn MULLER Zool. Danica (1788).] 



Body elliptical, a little convex on the upper side 

 and flat beneath, of a dull, sub-opaque brownish or 

 yellowish white in old specimens, more transparent 



