ASC'IDIA RUDIS. 101 



slender. Branchial wte green, with stout papillae at 

 the intersections of the meshes, and frequently with 

 intermediate ones on the longitudinal bars. Oral lamina 

 transversely ribbed. 



L<'it(/t/t about two inches and a half. 



Hal. Between tide-marks [and at low-water mark]. 



ENGLAND. Hastings, Sussex (Blackett and Boirer- 

 banJc). 



SCOTLAND. Near the Whalsey Lighthouse, Out Sker- 

 ries, Shetland [, 18(51, the type specimens] (Norman). 

 [Between the Islands of Whalsey and Balta (Norman, 

 18(37).] 



IRKLAND. Belfast Bay, Antrim (Thompson}. 



First record Alder, 1863 ; coll. Norman [1861]. 



The test (PI. VII, fig. 1) is richly supplied with vas- 

 cular ramifications, the ultimate twio-s being 1 verv 



o o / 



numerous and minute ; and the mantle (PI. VII, fig. 2) 

 is delicate, with few and irregularly-disposed muscular 

 til >res 



The branchial sac (PL VII, fig. 3, and PI. XVII, 

 fig. 8) is minutely plicated, and the longitudinal bars 

 correspond in number and direction to the plications, 

 which are distinctly defined. The papillae are large, 

 obtuse, and somewhat arched, with w ell-developed 

 intermediate small ones ; the larger are placed at the 

 angles of the meshes formed by the bars crossing the 

 primary vessels, and, as the meshes are rather small, 

 the papilla? appear crowded, especially as the inter- 

 mediate ones are of considerable size. The primary 

 vessels are pretty regular in size, but there are a few 

 larger at irregular intervals ; and on the outside of the 

 sac, they and other vessels which proceed from them, 

 chiefly at right angles, are strongly papillose. The 

 oral lamina is moderately developed and has the right 

 side ribbed, and the tentacular points, extending from 

 the left side of the mouth dow r nwards to the bottom of 

 the sac, are much larger than usual, and are, for the 

 greater portion of their length, free. The tubercle is 



