32 BULLETIN 16G, UNITED STATES NATIONAL MUSEUM 



ETHUSA MICROPHTHALMA Smith 



Plate 22, Figure 3; Plate 23, Figure 3 



Ethusa microphthalma Smith, Proc. U. S. Nat. Mus., vol. 3, p. 418, 1881 (type 

 locality, off Marthas Vineyard, Mass., 142)^^ fathoms, station 878, Fish 

 Hawk; type, U.S.N.M. no. 7300); Proc. U. S. Nat. Mus., vol. 6, p. 22, 1883. 



Diagnosis. — Eyestalks longer than cornea. Dactyli of first and 

 second ambulatories vertically compressed. Appendages of second 

 abdominal segment of male shorter than those of first segment. 



Description. — Carapace as broad as or broader than long, very 

 much narrowed anteriorly so that in front it is only half or less than 

 half as broad as the mdest part, wliich is at the swollen branchial 

 regions posteriorly. Front between the orbits half or less than half 

 as wide as the entire front and, as seen from above, is divided by a 

 triangular median sinus and two slightly less deep sinuses at the 

 extremities of the antennular fossae; the angles between and outside 

 these sinuses are spiniform, so that the front between the eyes is 

 armed with four similar and nearly equidistant spines, of which the 

 lateral are slightly more prominent than the median. Orbital 

 sinuses nearly as deep as broad and formed on the outside by the 

 spiniform anterolateral angles, which reach farther forward than the 

 spines of the front. Anterolateral margins long and nearly straight. 

 Dorsal surface slightly convex and not deeply areolated though the 

 cervical suture is well marked and the whole surface is granular and 

 pubescent. Ej^es small, on very short peduncles, so that they do not 

 nearly reach the angles of the orbital sinuses; cornea terminal, not 

 expanded, pigment black. 



Chelipeds of female equal, small and very slender; chela scarcely 

 stouter tlian carpus, the basal portion smooth and nearly cylindrical 

 and the digits alike, fully as long as the man us, strongly compressed, 

 longitudinally grooved, slightly curved laterally, prehensile edges 

 nearly straight, and very regularly dentate. Chelipeds of male 

 very unequal, the left is slender like those of the female, the right is 

 considerably longer than the left and has a stout and swollen chela, 

 about four times as high and two and one-half times as thick as the 

 left; the fingers much shorter than the manus, tapering to the tip, 

 prehensile edges oblique and unarmed ; carpus and merus much longer 

 and stouter than in the left cheliped. The first two pairs of ambu- 

 latories are twice as long as the minor cheliped and nearly naked, 

 propodus shorter than merus, slightly grooved longitudinally, dac- 

 tylus longer than propodus, much compressed vertically, slightly 

 curved, of nearly uniform breadth to a short distance from the 

 acuminate tip, and strongly carinate. Third and fourth pairs of 

 ambulatories nearly alike, not half so long as first and second, slender, 

 and covered with short pubescence except on the dactyls, which are 

 very short and strongly curved. 



