's RIJKS MUSEUM VAN NATUURLIJKE HISTORIE — LEIDEN. 457 



This last character, as also the conspicuous spiniform granules on the 

 carapace, are sufficient to separate this species at once from all its con- 

 geners. The front is very narrow, strongly constricted between the base 

 of the ocular peduncles and bilobed at its free margin. The eye-stalks 

 do not reach beyond the external orbital angle. 



Judging after my material, which consists only of four specimens, the 

 species is subject to considerable variation. Firstly two specimens (males) 

 exhibit a much more spinous carapace than the females; in the first case 

 the granules are distributed over the whole surface (though more con- 

 spicuous and larger on the branchial regions than on the mesogastric 

 and cardiac area) ; in the females on the contrary the middle regions of 

 the carapace are nearly perfectly smooth, with only very few scattered 

 granules, on the branchial regions the granules are large, knob-like 

 and of the same character as those in the males, but somewhat fewer in 

 number, and disposed in an irregular longitudinal row. I sup- 

 pose such females have induced Milne-Edwards to erect a distinct species 

 (Guérini), the carapace of which is „à peine granulée" and granulated 

 only on the branchial regions, „où les plus gros sont disposés en une 

 série longitudinale". 



Secondly the spines on the legs are very much variable. The meropo- 

 dites of the middle pairs of walking legs may be very spinous on the fore 

 margin or only tuberculated in both sexes. Alcock says that only in the 

 penultimate pair of legs the hinder border of the propodite is serrated, 

 but the propodite of the second pair may exhibit this same character, 

 though it is smooth in other cases, in such a way, that the right or left 

 walking legs of the second pair may differ in this respect from those of 

 the other side. For this reason I am much inclined to regard the 

 M. simplicipes of Guérin as another (young) variation of M. pectinipes, 

 indeed it differs only from this last species by having the legs perfectly 

 smooth, not spinous but hairy, whereas the form of the carapace with 

 its large spiniform granules, the shape and direction of the outer orbital 

 angle and of the lateral teeth, are exactly the same as in M. pectinipes. ! ) 

 Even the rounded tubercles of the ventral border of the orbital groove 

 (in the male) are indicated in Guérin's figure of M. simplicipes. 2 ) These 

 two species were found together in the same localities. 



The Leiden Museum possesses 4 specimens (dried), without indication 

 of origin. 



1) In Guérin's figure of M. peçtinipes the second lateral tooth is omitted, though it is men- 

 tioned in the text. 



2) This author says that the form of the male abdomen in M. simplicipes is widely different 

 from that of M. pectinipes, bat he does not give any further detail nor figures. 



