546 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 50. 



strong, blunt- outer spines or teeth, the posterior of which is the 

 larger ; the tips of both are visible in dorsal view. 



Chelipeds half again as long as the carapace excluding rostrum; 

 merus snbcylindrical, increasing distally where it bears a few sharp 

 granules; manus somewhat compressed, two and a half times as long 

 as its greatest width and armed on the upper surface and the upper 

 half of the inner surface with sharp tubercles; fingers arched and 

 widely gaping for their proximal two-thirds. Ambulatory legs 

 slender, the first pair two-sevenths longer than cheliped ; spinules of 

 clactyli minute. 



Relationships. — In the rounded outlines of the branchial regions 

 this species reminds one of H. planasius ^ and of //. calvarius.'- H. 

 planasius has a flatter carapace, longer branchial spine, shorter, 

 broader horns, and shorter, stouter chelipeds, while H. calvarius is 

 smooth in its dorsal aspect except for a branchial and an intestinal 

 spine. The pair of cardiac tubercles and the character of the anten- 

 nal segment set the new species apart from all others, 



HYASTENUS FRATERCULUS, new species. 



Type-locality. — Tav^d Tawi Group, Sidu Archipelago: Observation 

 Island, N. 70° W., 6.4 miles; lat. 4° 58' 20" N.; long. 119'^ 50' 30" 

 E.; 9 fathoms: Co.; Feb. 24, 1908; station 5165, Albatross. 



Halotype.— Male. Cat. No. 48291, U.S.N.M. 



Measurements. — Length of carapace on median line, 7; length of 

 rostral horns, 0.7: width of carapace, 5. 



This species is so near II. biformis that it can best be described 

 by comparison. The carapace is posteriorly less rounded, the lateral 

 and posterior margins of the branchial regions being straighter; 

 the gastric region is ornamented with 3 prominent median tubercles 

 (instead of 2) and 2 tubercles (instead of one) on each side, ar- 

 ranged obliquely and almost in line wdth the middle of the median 

 tubercles; a marginal branchial roAv of 8 (on the left) or 9 (on the 

 right) tubercles, unequal in size; man}^ tubercles or granules on 

 the subbranchial and pterygostomian regions; intestinal region 

 produced obliquely backward in a large, blunt, conical elevation. 

 Rostral horns short and directed forward. Margins of manus of 

 cheliped more nearly parallel than in hiforrrds. Merus of first am- 

 bulatory leg armed with three tubercles above on the proximal half. 

 For the rest, much like hiformis., having a similar cardiac region, 

 orbits, antenna?, maxillipeds, and abdomen. 



1 Visa planasia Adams and White, Voy. Samarang, Crust., 1848, p. 0, pi. 2, flgs. 4, 4(7, 

 5, 5a. 



2 Compare Alcock and .\nderson, Illus. Zool. Investigator, Crust., pt. 4, 1896, pi. 21, 

 fig. 2. 



