4. Thydne (Rif^ALis.^''\ Subfusiform, of a broWnish-grey color, with the suck- 

 ers small, uaiformly aistributed over the whole surface. Anus with five cal-' 

 careous papillae. Tentacula much branched, ten in number, two of which are 

 much smaller than tlTe^n^st. The oral column is the most remarkable feature in 

 this species, it being about one-half as long as the body, and consisting of a 

 flexible calcareous cylinder, contorted below, and sending ten short spurs of 

 points upward, and five pairs of long twisted ones downward. Its flexibility is 

 owing to the circumstance that its calcareous matter is deposited in the form of 

 irregular plates connected by softer parts. The inferior spurs thus seem jointed. 

 Length, 2 inches ; breadth, 0.35 inches. Taken near low water mark, under 

 stones. 



Hab. Australia, at Port Jackson. 



5. Ghirodota Austbaliana. Small, and very slender ; surface covered with 

 papillae of two kinds ; the smaller and less conspicuous of which are spread 

 everywhere, and consist of accumulations of epiculae, which are hooked at one 

 extremity and slightly bent at the other. The larger kind are scattered, quite 

 thickly, along one side of the body only ; and are prominent, circalar, white, 

 calcareous, varying in size from l-40th to l-20th of an inch in diameter ; they 

 are composed of accumulations of minute, six-spoked wheels. The tentacula 

 are ten in number, each having ten serrulated digitations, placed on the outer 

 and the lateral margins of a sort of disk, which forms the anterior half of the 

 inner side of the tentacle. Color, pale yellowish. Length, 2 inches; breadth, 

 0.2 inch. Found under stones, near low-water mark. 



Hab. Australia, at Port Jackson. 



6. Synapta dolabeifesa. Slender, but rather short, of a dirty yellowish co- 

 lor ; skin very thickly provided with hook-bearing plates, which have usually 

 about ten perforations, the middle ones largest. The hamulae are a little larger 

 than the plates, pickaxe-shaped, with the extremity of the handle also provided 

 with a double hook, though of very small size. Tentacula twelve, digitate 

 nearly to their bases ; digitations short, about fourteen in number to each ten- 

 tacle. Length 2 inches. Found under stones, near low-water mark. 



Hab. Australia, at Fort Jackson. 



TUNICATA. 



7. Cynthia angularis. Small, elongated, with a small base, and seven or 

 eight longitudinal ridges ; test coriaceous, nearly smooth between the ridges, 

 of a pale yellowish color; apertures square, at the extremities of short tubes 

 which are placed close together at the extremity of the body ; each tube with 

 four longitudinal reddish bands corresponding to the angles. Length, 1 inch ; 

 breadth, 0.3 inch. On sea- weeds in the circumlittoral zone. 



Hab. Cape of Good Hope, at Simon's Bay. 



8. Cynthia l^evissima. Egg-shaped ; test very thick, of a pale orange 

 color, very smooth and glossy ; apertures small, red. Branchial sac with about 

 20 folds, and with twenty elongated, fimbriated tentacles at its apertures. Some 

 of these tentacles, as is usually the case in this genus, are much smaller than 

 the others. Length 1 inch. Found under stones in the lower part of the litto- 

 ral zone. 



Hab. Australia, at Port Jackson. 



9. Cynthia sabulosa. Eounded, laterally compressed, usually attached by 

 one or more short stalks. Test strong and hard, but not very thick ; surface 

 covered with sandy particles, which adhere so strongly as to form part of its 

 substance. Apertures on slight prominences, the branchial largest and dotted 

 with black. Branchial folds eight in number, narrower than their interspaces. 

 Branchial tentacles simple, filamentary, long and very numerous. Diameter 1- 

 inch. Found in the circumlittoral zone, on muddy bottoms. 



Hab. Australia, at Fort Jackson. 



