PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 497 



Tol. VII, ]Vo. 32, IVashingrton, D. €. Jan. 



1885. 



Measurements in millimeters. 



Catalogue number 



Station 



Ses 



Length from tip of roatrum to tip of telson. .. 



Length of caiapax. including rostrum 



Length of rostrum 



Greatest broa<lth of carapax, including spines 



Breadth at bases ot' antero-lateral spines 



Breailth at branchial regions ^ 



Ltni;th of eye-stalk, including spine 



Length of spine 



Diameter of eye 



Lengtli of light cheliped 



Lenglh of right chela 



Breadth of riglit chela 



Lcugth of dactylus 



Lensith of left cheliped 



Lengtli of l.ft chela 



Breadth of left chela 



Length of dactylus 



Length of tirst ambulatory periEopod 



Lt-ngt h of propodus 



Length of dactyins 



Lingi h of posterior peracopod 



Lenuth of telson 



Breadth of telson 



Lengt h of inuer lamella of uropod 



Breadth of inner lamella of uropod 



Leimt !i of outer lamella of uropod 



Breailth of outer lamella of uropod 



M. crassa. M. similis. 



Bythocaris gracilis, sp. iiov. 



This species is closely allied to B. Payeri G. O. Sars, and is possibly 

 only a variety of it, though the specimeus seen differ conspicuously 

 from si)ecimens of B. Payeri^ from the Faroe Channel, received from the 

 Kev. Dr. i^Torman, in the size of the eyes and the form of the antenna! 

 scales. 



Female. — The carapax is about two-thirds as broad as its length 

 along the dorsum, and the front about a sixth as broad as the length 

 and very nearly as in B. Payeri, but the lateral teeth are a little more 

 prominent than in that species. The short median carina on the gastric 

 region terminates abruptly in a small tooth anteriorly, not present in 

 any of the specimens of B. Payeri. The eye-stalk and eye are about a 

 fourth as long as the dorsum of the carapax, and the diameter of the 

 black eye about three-fifths of the length of the stalk and eye. In the 

 specimens of B. Payeri the eyes are considerably smaller, about a fifth 

 as long as the carapax, and the diameter about half the length of the 

 eye and stalk. The first segment of the peduncle of the antenuula is 

 armed with a very slender and acute lateral spine which reaches nearly 

 as far forward as the segment itself. The anteunal scale is fully as long- 

 as the dorsum of the carapax and less than a third as broad as long, 

 wliile in B. Payeri it is rather sliorter and considerably broader. The 

 pera-opods and pleon are very nearly as in B. Payeri. 

 Proc. Nat. :\Ius. <S4_ 



•)-, 



