Flattened part of carapace about as long (without rostrum) as 

 broad, nearly circular; external orbital angle a low rim; 

 walking legs long and slender, about 3 times the breadth 

 of the carapace. Abdomen of cf short, triangular, "reaching 

 only to the posterior margin of the sternum, corresponding to 

 the fourth pair of legs" (Chilton). Species of New Zealand H.depressum Jacquinot et Lucas 



I. Hymenosoma orbiciilare Desmarest. PI. i. Fig. i. 



For synonymy see Stebbing, Ann. S. A. Mus., v. 6, 1910, p. 331 — 332 and Stebbing, Transact. 

 R, Soc. Edinburgh, v. 50, prt 2, 1914, p. 270. .... 



The following records seem to have been overlooked by Stebbing : 



H. Milne-Edwards, Ann. Sc. Nat. (3) t. 20, 1853, p. 222, pi. 11, f. 2. 



Ortmann, Denkschr. d. med.-naturw. Gesellsch. Jena, Bd 8 (Semon's zool. Forschungsreisen, 



Bd 5, Lief, i), 1894, p. n- 

 Lenz, Abhandl. Senckenb. Gesellsch., Bd 25, 1905, p. 368. 



This characteristic South African species was not represented in the "Siboga" collection, 

 but I had the opportunity of studying a cf collected by Prof. Weber in Table Bay near Cape 

 Town, in 1894, ^ — '^ fathoms, sandy bottom. 



I have figured this species again, for none of the figures heretofore published, at least 

 as known to me, convey an exact idea of its outer appearance. The species has been figured 

 in its details by Stebbing (I.e., 1914, pi. 25 A), but clear and exact as these drawings are, I 

 hope not to do injustice to this highly-esteemed carcinologist in pretending that his figure of 

 the habitus of the animal is really insufficient. 



The flattened part of the carapace has a longitudinally-oval shape, semicircular posteriorly, 

 somewhat pointed in its anterior part. It is bordered by minute tubercles at the sides and passes 

 gradually into the rostrum, that is marked off behind its base by a feeble, convex rim. The 

 rostrum itself is short, concave at its surface, somewhat deflexed, and pointed at the tip; at 

 either side of the base there is a distinct callose thickening of the border. The eye-stalks are 

 short and thick; the corneas reach beyond the tip of the ^ rostrum. The sides of the carapace 

 are obliquely-sloping outward, so that the total breadth of the carapace is equal to the length, 

 not including the rostrum; these sloping sides are beset with numerous minute tubercles, and 

 unite at the hind margin, between the bases of the hind legs, with the bordering rim of the 

 flattened part; this rim, moreover, consists of two parts, separated off in the middle of its 

 course; the posterior part passes very obliquely forward on the sloping sides of the carapace, 

 thus marking off a hepatical and a branchial region. On the former region there are two 

 obtuse prominences, that are themselves minutely tuberculate, the posterior directed upward, 

 the anterior forward. The external orbital angles are situated beneath the level of the deflexed 

 tip of the rostrum and reach as far forward as this tip ; they are sharp, spine-like, and bifid; 

 upper and lower margin of the orbit are practically absent, the orbit itself passing imperceptibly 



into the buccal cavern, as the epistome is wanting. 



6 



