544 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 50. 



tAvo leading obliqiiely-transversely forward on each side of the an- 

 terior median tubercle, those of the inner pair very small; branchial 

 region w ith a lateral row of four tubercles arching upward, the pos- 

 terior of these being at the postero-lateral angle; a tubercle on the 

 areola at the inner angle of the branchial region, between the cardiac 

 and intestinal regions; a small but prominent tubercle on the hepatic 

 margin; two large and one small pterygostomian tubercle. Eostral 

 horns widely divergent, slender, arched upward. Anterior end of 

 preorbital hood subrectangular, not produced. On the basal seg- 

 ment of the antenna, a blunt tooth or spine obliquely placed, visible 

 from above, followed on the outer margin by a large lobe and then 

 by a tubercle. 



Chelipeds equal in length to the carapace and nearly half the 

 rostrum; palms swollen, pubescent, a small tubercle on upper margin; 

 fingers proximally arched, making a wide gape for half their length. 

 Spinules on dactyli of ambulatory legs rather small. 



Relationships. — This species suggests II. Mlgervdorf., but the cara- 

 pace is wider across the anterior part and the preorbital cup is not 

 produced and pointed as in hilgendorji\ the prominences are simi- 

 larly arranged, but none of them are spines; the manus of the adult 

 male is shorter and wider and not wholly smooth, as in that species. 

 On the other hand, the shape of carapace and orbit and especially the 

 profile view, are very like II. elongatus (Ortmann),^ but the carapace 

 is wider in proportion to its length, also smoother, the horns shorter 

 and more spreading, the legs shorter, especially those of the first pair, 

 the propodus of which is one and a half times longer than the carpus 

 (in elongatus twice as long). 



HYASTENUS ORBIS, new species. 



Type-locality. — Tawi Tawi Group, Sulu 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 51G5, Alha.tross. 



II olotype.— Ovigerows female. Cat. No. 48216, U.S.N.M. 



MeasureTnents. — Length of carapace on median line, 8; length of 

 horns, 2.2; width of carapace, 5.1. 



A small species, relatively wide, with large orbits; cardiac higher 

 than gastric region, the latter sloping steeply doAvn from the summit 

 to the base of the horns. Five median tubercles of which three are 

 gastric, one cardiac, one intestinal; a transverse row of four tubercles 

 on the gastric region in a line between the anterior and the second 

 of the median tubercles; a pair of tubercles behind the rostrum and 

 forming an equilateral triangle with the anterior median tubercle; 

 curve of four acute tubercles or spines on the margin of the branchial 

 region, the posterior of which is longer and definitely spinate; three 



^Hyastenus diacanthus var. elongata Ortmann, Zool. Jahrb., Syst., vol. 7, 1893, p. 55. 



