620 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxviii. 



Of the grooves separating- the carapace areas, the crossbar of the 

 "■H"is much farther forward than in the preceding- species, four- 

 ninths, or nearly half, the distance from the posterior margin. More- 

 over, it is strongl}' curved forward, and, together with the posterior 

 portion of the lateral grooves, it forms a nearl}- perfect semicircle. 

 The lateral grooves are not parallel with the margin of the carapace, 

 but diverg'e widely from it. The eyes are smaller than in innominatm^ 

 but are situated in about the same relative position. 



The free thoracic segment is less than half the width of the genital 

 segment, snbtriang-ular in shape, and narrowed into a neck anteriorly 

 where it joins the carapace. This is in marked contrast with Itrnomi- 

 natiix^ the anterior margin of whose free segment is its widest part. 



The genital segment has an elongate flask shape, narrowed into a 

 neck anteriorly, and then widening- to about two-thirds the w^idth of 

 the carapace. It is one-fourth longer than wide, with a deeply emar- 

 ginate posterior border and well-rounded lobes at the angles. The 

 abdomen is two-tifths the width of the genital segment and two and a 

 half times as long as it is wide. 



It is two-Jointed, the basal joint nearly three times as long as the ter- 

 minal. The abdomen is somewhat swollen at the joint, and then tapers 

 rapidly toward the tip. The anal lamina^ are small and widel}" sepa- 

 rated, with the tips curved in toward each other. The setffi are also 

 very small and slender. 



The Qgg strings are only half the diameter of the abdomen and about 

 as long as the entire ])od3\ The eggs are thick, and number 125 or 130 

 in each string. 



The first antenna^ are relatively smaller than in hinominatus^ but are 

 as well provided with seta^ and spines; the second pair are small, with 

 a short terminal hook. 



Both pairs of maxillae are slender, the second pair divided nearly to 

 their base with narrow, slender, divergent branches. 



The furca is relatively large, fully twice the size of that in liino- 

 iiilnatuK; it is strongly narrowed at the base and then widens into a 

 broad U-shape, with dilated branches. 



The second maxillipeds are large but not to be compared with those 

 in Innoinl-natus for size; the terminal claw is nearly as long as the basal 

 joint, but rather slender and strong-ly curved. 



The first swimming legs have a stout spine on the posterior margiii 

 of the basal joint and another at the anterior distal end of the second 

 joint, with the usual set{\3 and terminal spines on the last joint. The 

 fourth legs are short and small, four-jointed with five spines; but 

 one of the spines is at the outer distal corner of the basal joint and 

 there is none on the second joint. These legs are about one-third the 

 length of the genital segment. The fifth legs are invisible in a dorsal 

 view. 



