MUSEUM OF COMPARATIVE ZOOLOGY. 



51 



lateral spine of the sixth somite is smaller and not directed so much backward. 

 There are no differences of importance in the form of the telson, uropods, or 

 other abdominal appendages. 



The eggs are slightly larger than in R. Agassizii, and of about the same 

 number. 



The specimen above described gives the following measurements : — 



Length from tip of rostrum to tip of telson 

 Length of carapax, including rostrum . . 



Length of rostrum 



Breadth of carapax in front, including spines 



" " at cervical suture 



" " at middle, including spines 



Length of antennal scale 



Breadth of antennal scale .... 



Diameter of eye 



Length of external maxillipeds 



" first pair of legs .... 



" second pair of legs 



" merus 



" carpus 



" chela 



" third pair of legs .... 



" fifth pair of legs .... 



" telson 



. 108.0 mm 



44.0 

 . 18.5 



19.3 

 . 15.4 



21.5 



. 12.7 



6.8 



. 5.5 



22.5 



. 22.2 



right, 29.0 ; left, 27.5 



6.2 

 12.7 



1.1 



6.2 

 11.0 



1.1 

 34.0 

 27.5 

 18.5 



Station 339, N. Lat. 38° 16' 45", W. Long. 73° 10' 30", 1186 fathoms. 



Rhachocaris longirostris, sp. nov. 



Plate V. Figr. 1. Plate VI. Fig. 1. 



Female. — This species agrees with R. Ayassizii in having the dactyli of the 

 fourth and fifth pairs of thoracic legs slender, but in the sculpturing of the 

 carapax and abdomen it is more like R. sculpta, though the tubercles are fewer 

 in number and are all obtuse ; it differs very conspicuously from both these 

 Bpecies in having a much longer rostrum, longer telson, much shorter antennal 

 BCales, and the eyes on shorter peduncles, and, in the alcoholic specimen, devoid 

 of colored pigment. 



The rostrum is slightly longer than the rest of the carapax along the dorsal 

 line; the basal two-thirds is horizontal, but the tip strongly upturned ; the 

 upper side is tint and the horizontal portion of uniform breadth, but the tip 

 regularly tapered and acute ; there is a slight median carina the whole length ; 

 there are lateral spines and the corresponding pair of spines at the ba.se of the 



