160 PEOCEEDINGS OF THE ACADEMY OF 



encrusting matters, corrugated both longitudinally and transversely ; the 

 longitudinal plications are frequently strongest and most regular, but often 

 they are rendered irregular or nearly obliterated by the transverse ones. 

 The apertures are placed near together at the extremity of the body on 

 slight protuberances, which are probably produced in life into short tubes. 

 Branchial sac with ten slight longitudinal folds, not lamelliform ; filaments 

 at its summit numerous, small, slender and simple. 



The largest specimen is 1*4 inch in length, and 0-6 in breadth. 



According to Dr. Kennerly's notes, this species was dredged by Lieut. 

 "White at the following places : Port Townsend, in 4 fathoms, shelly bottom, 

 and also on a muddy bottom in 10 fathoms. Off the N. W. end of Lummi 

 Island, in 15 fathoms, 6helly bottom. 



The dedication of this fine species to one so well known upon the survey as 

 Mr. George Gibbs, is scarcely necessary to indicate the great interest he has 

 taken in its scientific results. 



Cynthia coriacea. 



A tough, unornamental species, with no very strongly marked characters. 

 It is irregularly egg-shaped, and attached by a broad surface on the right 

 side of the body. The test is free from agglutinated matters, smooth, and 

 scarcely at all wrinkled, except about the apertures, which are on rather large 

 protuberances, probably extensible in life into short tubes. The branchial 

 aperture is largest, and situated at the -extremity of the body; the anal a 

 little behind the middle of the upper side. Branchial sac with about the 

 same number of folds as in the preceding species, which are, however, very 

 prominent and lamelliform, being broader than half the width of the inter- 

 spaces. The filaments at the summit of the branchial sac appear to be few, 

 and shaped like the palpi of the bivalve acephala. 



From the slight indications yet observable in the specimen, it would seem 

 to have been of a reddish color when alive. 



It was found upon the "shore of Island No. 2, off Salt Spring Island, March 

 9, 1859," by Lieut. White, of the Revenue Cutter. 



Cynthia villosa. 



Of similar size, and allied to the C. echinata of the North Atlantic, of which 

 this is the analogue or representative species on the west coast. It is, how- 

 ever easily to be distinguished from that species by the character of the vil- 

 losity or short, hair-like processes with which the test is covered. These are 

 shorter, more numerous than in C. echinata, and not provided with radiating 

 hairs at the summit, being simply tapering to a fine extremity, and sparsely 

 pubescent on their sides. 



The base of attachment in this species is very small, and the test at that 

 point is produced into a peduncle, which is sometimes as long as the body is 

 thick. This peduncle is, however, entirely similar to the test in character, 

 and not at all like that of Bdlenia. Our largest specimen is about 0-6 inch 

 in diameter. 



Dredged by Lieut. "White in "Port Townsend, 10 fathoms, muddy bottom," 

 and " off the N. W. end of Lummi Island, in from 8 to 15 fathoms, on shelly 

 bottoms, March 2d and Feb. 22d, 1859." 



Genus CHELYSOMA, Brod. and Sow. 



The "tortoise-shell" Ascidians, which form the curious arctic genua 

 Chelt/soma, have the posterior extremity of the body flattened, forming an 

 oval disk with a raised margin, and the surface divided into polygonal plates. 

 But two species have been hitherto known, the C. Macleayana, from Green- 

 land, and C. geomelrica (Ascidia geometrica Stm., Mar. Invert, of Gr. Manan.) 



[June, 



