DB. W. A, HEBDMAN ON BEITISH TTJNICATA. 279 



Mantle moderately muscular on the right side. 



Branchial sac extending beyond the viscera posteriorly, longi- 

 tudinally plicated (in some parts not at all strongly) ; meshes 

 square or slightly elongated transversely, with stout papillae at 

 the corners, and smaller intermediate more conical ones. Stig- 

 mata short, generally oval or elliptical, three in a mesh. 



Dorsal lamina narrow, ribbed transversely, margin bluntly 

 denticulated. 



Tentacles small and distant, 25 to 30 in number, large and 

 small alternately. 



Olfactory tubercle almost quadrangular in outline ; both horns 

 coiled inwards. 



Nerve ganglion oblong, narrow, placed nearer the atrial than 

 the branchial aperture. 



Locality. Upper end of Loch Long, 5 to 10 fathoms. 



This species is evidently allied to Ascidia mentula. 



One of the three specimens is a sinistral individual. The area 

 of attachment is on the right side, and the atrial aperture is on 

 the left. Internally, the branchial sac is placed to the left of 

 the viscera, so that, on opening the branchial sac from the side 

 opposite the viscera, the anterior end being uppermost, the dorsal 

 lamina is seen on the right hand and the endostyle on the left, 

 the reverse of the usual arrangement. 



Ascidia vieginea, O. F MUller. (Plate XV. figs. 1, 2.) 



Ascidia virginea, 0. F. Milller, Prodromns, p. 225. no. 2732 (1776), 



Zool. Ban, vol. ii. p. 12, tab. 49. fig. 4 (1780). 

 Ascidia opalina, MacGillivray, Moll. Aberdeen, p. 312 (1843). 

 Ascidia punum, MacGillivray, Moll, Aberdeen, p. 312 (1843) ; non 



Muller, Zool. Dan. 

 Ascidia sordida, Alder, Cat. Mar. Moll. Northumb. fy Durham, in Trans. 



Tynes. Nat. F. C. vol. i. p. 199 (1850). 

 Ascidia virginea, Alder, Cat. Mar. Moll. Northumb. fy Durham, in Trans. 



Tynes. Nat. F. C. vol. i. p. 200 (1850). 

 Ascidia virginea, Forbes Sf Hanley, Brit. Moll. vol. i. p. 33 (1853). 

 Ascidia sordida, Forbes fy Hanley, Brit. Moll. vol. ii. p. 372 (1853), 

 Ascidia virginea, Norman, Moll, of the Firth of Clyde, Zoologist, vol. xv. 



p. 5708 (1857). 

 Ascidia virginea, Grube, Die Insel Lussin und Hire Meeresfauna, p. 53 



(Breslau, 1864). 

 Ascidia sordida, Hancock, Anat. fy Phys. of Tun., Journ. Linn. Soc, Zool, 



vol. ix. p. 309 (1868). 



