278 BE. W. A. HEEBMAK OF BRITISH TTTITCCATA, 



riglit side, especially in the centre, where the bands attain a 

 thickness of 5 millim. ; sphincters not particularly strong. 

 Mantle very thin on visceral (left) side ; no muscle-bands, JSTo 

 ocelli visible (spirit specimen). 



Branchial sac large, extending beyond the viscera posteriorly, 

 longitudinally plicated. Transverse vessels wide and rather 

 close, all one size. Meshes nearly square, the transverse extent 

 being generally slightly the greater, with large papillae at the 

 angles, and slightly smaller intermediate ones on the inconspicu- 

 ous internal longitudinal bars. Stigmata oblong, rather short, 

 six to eight in a mesh. All the larger vessels bear, on their outer 

 (atrial) sides, short, more or less spine-like projections. 



Dorsal lamina rather narrow, ribbed transversely, margin 

 slightly pectinated. On the right side of the branchial sac near 

 the dorsal lamina, and a little above the oesophageal opening, 

 there is an oval slit 1*5 centim. long ; externally it opens just inside 

 the atrial aperture. 



Tentacles few (16 to 20), distant, and rather small, filiform. 



Olfactory tubercle of moderate size, irregular in shape, right 

 horn rolled outwards and left horn inwards. 



Viscera, — Stomach large, thick- walled. Intestine with a broad 

 typhlosole projecting from the upper (inner) side. Ovary and 

 testis placed in the loop. 



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



This species externally bears considerable resemblance to 

 Ascidia mentula ; it differs from it chiefly in the character of the 

 branchial sac, the tentacles, and the olfactory tubercle (see 

 Plate XIY. fig. 3). 



Ascibia rusiroRMis, n. sp. (Plate XIY. figs. 4-6.) 



External appearance. — Shape elongate-elliptical, flattened late- 

 rally ; both ends narrow, anterior almost pointed, posterior 

 more obtuse ; dorsal edge rather more convex than ventral. 

 Attached by a small area on the left side two thirds of the way 

 down. Branchial aperture terminal and median, almost sessile ; 

 atrial on right side halfway between median line and dorsal 

 margin, fully halfway down, sessile ; lobes of both rather in- 

 distinct. Surface smooth, a few faint mostly longitudinal creases 

 on the right side. Colour light. yellowish grey, hyaline at the 

 edges. Length 6-5 centims., breadth 3 centims. 



Test rather thick, hyaline, transparent; vessels just visible. 



