194 BULLETIN OF THE 



Family CALOCARID^J. 



CALASTACUS, gen. nov. 



Abdomen long, enlarged in the middle, narrowed at each extremity, pleurae 

 broad and rounded. Cephalothorax laterally compressed, rostrum long, acute ; 

 eyes rudimentary, subglobose, unpigmented, unfaceted. Second antenna on 

 a horizontal line with the first antenna ; the second segment armed with a 

 long external spine (stylocerite) and a still longer articulated style-shaped 

 scale (scaphocerite). Third maxilliped pediform. First and second pairs of 

 legs chelate. First abdominal appendages of male modified to serve as sexual 

 organs (gonopods). Outer branch of swimmerets divided near the posterior 

 margin by a diagonal suture. Telson long, quadrangular. Gills composed of 

 a central stem which bears two rows of filaments. Branchial formula : 



Somite 



VIII. 



IX. 



X. 



XL 



XII. 



XIII. 



XIV. 



Epipods . . . 



. 1 



1 



1 



1 



1 



1 



= 6 



Podobranchiae . 



. 



1 



1 



1 



1 







= 4 



Arthrobranchiae 



. 



2 



2 



2 



2 



2 



= 10 



Pleurobranchiae 



. 























= 



Differs from Calocaris in having a long styloid scaphocerite appended to the 

 peduncle of the external antennae. 



Calastacus stilirostris, sp. nov. 



Carapace naked, punctate ; apex of rostrum turned a little upward ; two 

 strong -spines turned upward and forward at base of rostrum ; a light median 

 carina runs along the back from the base of the rostrum, fading out before 

 reaching the hind border of the carapace. Chelipeds long, symmetrical on the 

 two sides ; coxa furnished with a small spine on the anterior border of the dis- 

 tal end ; ischium armed with from one to four spines on the lower margin ; 

 merus laterally compressed, armed with a spine on the upper edge near the 

 distal end and a variable number (four to eight) of spines on the lower edge. 

 Carpus triangular, unarmed. Chela : upper and lower margins sharp, the 

 upper armed with five to seven spines, inner and outer faces with a few scat- 

 tered spinules; fingers with denticulate prehensile edges and curved crossed 

 extremities. Second pair of legs furnished with small chelae. 



Length of carapace, 22.2 mm. ; rostrum, 5.5 mm. ; abdomen, 30 mm. ; 

 cheliped, 39 mm. ; chela, 17 mm. 



Station 3418. 660 fathoms. 9 males. 



