42 BULLETIN OF THE 



• 



ovate, tbe entire margin ciliated, and with the tooth of tbe outer margin small 

 and far back from the tip. The other parts of the antenna are nearly as in 

 Crangon. The oral appendages are very similar to those of Crangon and the 

 closely allied genera, and the labrum, metastoma, mandibles, maxillae, and 

 second pair of maxillipeds are very nearly as in Crangon vulgaris. In the first 

 maxilliped the proximal lobe of the endopod projects inward much more prom- 

 inently and the distal lobe is longer than in Crangon. There are two arthro- 

 branchiae at the base of the external maxilliped, as in Sabinea, and the stout 

 endopod is composed of three segments as in Crangoninae, but the two distal 

 segments are very short and the terminal one acute and spined. 



The legs of the first pair are symmetrical and about as large as the external 

 maxillipeds ; the propodus is short and tapers distally, and the dactylus is small, 

 slender, and capable of flexion against the inner side of the propodus. The 

 legs of the second pair are elongated, slender throughout, and, in all the speci- 

 mens examined, slightly unsymmetrieal in length ; the carpi are long and 

 muiltarticulate ; and the chela? small. The last three pairs of legs are slender 

 and nearly alike. 



The number and arrangement of the branchiae differ from all the Crangonidse 

 known to me. In R. sculpta, the second species here described, there are 

 epipods on the bases of the first and second maxillipeds and two arthro- 

 branchiae at the base of each external maxilliped, one arthrobranehia for each 

 of the thoracic legs except the last pair, and a pleurobranchia for each side of 

 the last five thoracic somites, — making two epipods, six arthrobranehia?, and 

 five pleurobranchiae each side, as indicated in the following formula : — 



ii+OO 



The abdomen is sculptured and spined to correspond with the carapax, and 

 the ezoskeleton is throughout very thick and massive. 



In the three species here described, the hinges at the last three articulations of 

 the abdominal somites — that is, at the articulation of the tilth with the fourth, 

 tin- sixtli with the fifth, and of (he telsotl with the sixth — present a peculiar 

 modification by which the hinge is very much strengthened ami is at the Bame 

 time apparently made capable of being clamped or locked so as to hold the 

 terminal somites firmly extended. In addition to the ordinary hinge, at each 

 of these articulations, there is a process arising from the anterior somite just 

 below the hinge and curved backward and upward concentrically with the 

 binge, and this process lit> accurately and is slightly overlapped along its edges 



by a similarly curved groove in the posterior somite. When the abdomen is 

 completely fiexed the ends of these curved processes projed dorsally consider- 



