156 Memoirs of the Indian Museum. [Vol. V, 



ture female, 6-5 mm,, and four newly hatched young. Types. — Regd. No. 8433/10, 

 Ind. Mus. 



Description. — This species is intermediate in its characters between G. spinifer, 

 Goes, and the species described above, G. muticus. Iyike both these species it pos- 

 sesses a fringe of from six to eight slender spine-like filaments on the central dorsal 

 posterior margin of the carapace and is therefore distinguished from every other 

 described species of the genus. 



In the three adult females and single adult male, there is no spine-like process on 

 the fifth segment of the pleon. But in the single immature female and in all the 

 newly-hatched young, this spine-like process is present, well developed and exactly 

 as seen in adult specimens of G. spinifer. The inference is naturally that in the pre- 

 sent species, the spine-like process is characteristic of the young and immature forms, 

 and disappears with the attainment of sexual maturity. My material is too scanty 

 to be definite on this point, but either my inference is the correct interpretation of 

 the facts, or there are two closely allied species present in the gathering. I have 

 judged of the maturity of my specimens by the state of development of the marsupial 

 lamellae in the female and of the third pleopods of the male. It is certainly sugges- 

 tive that the single female with the marsupial lamellae just appearing and the four 

 newly-hatched young should all have the spine-like process well developed, while the 

 obviously adult male and females should be without that process. The value of the 

 presence or absence of this process as a specific character is likewise very much 

 impaired if the above interpretation of the facts is the correct one. More material of 

 the species is greatly to be desired to settle this point. In the character of the 

 antennules, antennal scale, inner and outer uropods, and thoracic limbs, G. simulans 

 agrees exactly with the description given for G. muticus above. The telson, however, 

 has only from eight to ten spines on its lateral margins and is thus intermediate in 

 this respect between G. spinifer , where the number is six to eight, and G. muticus 

 with fourteen. 



The pleopods of the male and female agree essentially with those described for 

 G. spinifer, G. sanctus and G. muticus, except in the form of the exopod of the third pair 

 in the male, and it is on the character of this appendage that I have relied for the 

 institution of this new species. 



The exopod of the third pair of pleopods of the male is elongate, reaching to the 

 base of the telson. It is five-jointed, like the same appendage in both G. muticus and 

 G. spinifer, but stouter than in the latter species, and perhaps slightly more slender 

 than in the former. The first two joints are longer than the same joints in G. muti- 

 cus, and combined are longer than the third joint instead of being equal to it as in 

 G. muticus. The third joint is the longest and most slender. The fourth joint is 

 markedly longer than in G. muticus, but has the lower distal margin produced into an 

 obtuse lobe as in the latter species. The fifth joint is only slightly longer than the 

 fourth, but more slender and not broadened out at its apex as in G. muticus. The 

 apex of this joint bears a long slender curved spine minutely spinulated along the 

 distal half of its inner margin. This spine is considerably longer than is the same 



