76 PEOCEEZ)INGS OF THE NATIONAL, MUSEUM. vol.60 



appears in dorsal view only as a narrow neck between the posterior 

 lobes of the carapace and is less than one-fourth the width of the 

 head. The second, third, and fourth segments are abruptly widened 

 to equal the carapace, with sharply convex lateral margins. Along 

 the anterior border of these segments on either side is the rudiment 

 of a dorsal plate appearing in the form of a thickened margin, 

 which projects slightly. The fused posterior body is a little nar- 

 rower than the fourth segment, about six times as long as wide, 

 with nearly straight sides. It shows no traces of segmentation, but 

 is divided quite regularly by the attachment of transverse rows of 

 dorsoventral muscles. The egg strings are attached to its posterior 

 margin close to the midline and over the base of the abdomen, and 

 are longer than the entire body. The abdomen is about half as 

 wide as the genital segment, one- jointed, and obliquely truncated 

 at its posterior corners, to which are attached the anal laminae. 

 These latter are lanceolate, somewhat flattened dorsoventrally, and 

 taper to an acute point. Each is about one-third as long as the 

 entire body, is eight times as long as wide, and is destitute of spines 

 or setae. 



The first antennae are indistinctly three- jointed and tapered, with 

 a tuft of short spines at their tip. The second antennae are evidently 

 the chief organs of prehension, and project nearly their whole length 

 in front of the anterior margin. Each one is made up of a stout 

 basal joint and a strongly curved terminal claw, which is usually 

 carried at right angles to the basal joint, thereby increasing its hold- 

 ing power. 



The mouth tube is short and rather wide and tapers to a blunt 

 point. On either side of its base are the first maxillae, which are 

 filiform, three-jointed, and destitute of setae or claws. The second 

 maxillae are attached just outside of the first pair and are also three- 

 jointed. The basal joint is swollen and filled with powerful muscles; 

 the second joint is rather slender, its outer margin is crenate and is 

 armed with a row of short spines; the third joint is in the form of a 

 small curved claw. 



The maxillipeds are powerful prehensile organs ; the terminal claw 

 has a sharp spine or tooth on its inner margin near the center. 



The first swimming legs project from the sides of the first segment 

 just inside the basal joints of the maxillipeds and so close to them 

 as to be partially concealed. Each is made up of a single flattened 

 lamina without setae or spines. The second and third swimming 

 legs are on the ventral surface of their respective segments; the 

 second pair is biramose, the rami one- jointed, the exopod armed with 

 four spines, and the endopod with three. At the outer corner of the 

 basal joint, outside the exopod, is a large curved spine, longer than 



