18 Records of the Indian Museum. [Vou. VII, 
little doubt that all are correctly referred to the species described 
in the ‘ Challenger’ Report. 
The resemblance of the species to the well-known Medi- 
terranean form, A. foltacea (Risso), is very striking and Bouvier 
in his account of the Peneidae collected by the Prince of Monaco 
(1908, p. 56) was unable to determine the distinctions with any 
degree of precision. On comparing the two species, however, 
several characteristic differences may be observed. 
The rostrum in both sexes is shorter in A. voséyidentata than 
in specimens of A. foliacea of larger size. In the single female 
example of the former species, the rostrum trends more strongly 
upwards towards the apex than in specimens of 4A. foliacea of 
the same sex, while in male A. vostridentata it reaches only to 
the end of the basal joint of the antennular peduncle and its 
lateral carina is straight, or slightly concave ventrally, showing 
no trace of the sinuosity seen in male A. folzacea. 
But perhaps the most important distinction is to be found 
in the areolation of the carapace. The pterygostomian region 
is much broader in proportion to its length in A. vostridentata 
than in A. foliacea and the same is true of the branchial region, 
though the differences in this case are not so well-marked. In 
A. rostridentata the length of the pterygostomian region (measured 
from the antero-lateral margin of the carapace to the postero- 
dorsal end of the hepatic groove) does not exceed 2°5 times 
its greatest breadth, while it is more than 3°5 times as long 
as broad in A. foliacea (cf. figs. 5 and 6, pl. i). The ridge defining 
the upper boundary of the branchial region is, moreover, slightly 
less sinuous in the Indo-Pacific species. 
The specimens examined yield the following measurements 
(in mm.) :— 
a (Gee AS es A. foliacea (Risso). 
Sex A = 3 ©) a rea ¢ “3 ¢ co 
Total length .. -- | 149 |ca@.125|\ca.119|c@.215|ca.215| 170 | 137 
Length of rostrum 25) 2) a I oR | Ut eyo 41+] 14 
Length of carapace eect cA A050) 37 57 GR 41 38°5 
Length of pterygostomia 
region .: fei 1753). 4605 ES 7a 25 baal p23e5 18.73 9) D7, 
Breadth of pterygostomian 
region i a ios 72 Gj 6°5 6'5 4°5 4°5 
Ratio of length to breadth 
of pterygostomian region. . 2A) ness a2 3°9 3°6 470] 3°8 
In other respects there appears to be an extremely close 
resemblance between the two forms, but the dactyli of the 
last two pairs of peraeopods, which, in the specimens of A. rvostrt- 
dentata, are unfortunately broken off in all but two instances, 
appear to be longer than in A. foliacea and measure more than 
half the length of their respective propodites. The telson, also, 
