378 Records of the Indian Museum. [Vor 2ebr, 
1899. Pontocavis media, Alcock and Anderson, Ann. Mag. Nat. Hist. 
(7), LIL pp. 282. 
1900. Pontocaris propensalata, Whitelegge, Mem. Australian Mus., 1V, 
p. 198. 
1901. Aegeon medium, Alcock, Cat. Indian deep-sea Crust. Macrura and 
Anomala, p. 120, and JIlust. Zool. ‘ Investigator,’ pl. xli, fig. 6. 
In this case also I am indebted to Dr. Calman for the elucida- 
tion of the svnonymy. Dr. Calman has kindly compared co-types 
of A. medium with the type of Bate’s P. propensalata and has sent 
me the following note on the subject.—‘‘ I cannot find any differ- 
ence between the type of P. propensalata and A. medium. The 
sculpturing of the abdominal somites is less sharp in the former 
and the serration of the supramarginal carina of the carapace is 
very obscure—as it tends to be in the smaller of the two speci- 
mens of A. medium that I have examined.”’ 
The only specimens in the Indian Museum are those described 
by Alcock from the Andaman Sea, 55-66 fathoms. Bate’s type 
specimen was obtained off the Ki Is., south of New Guinea, 5°49’ 
15”S., 132° 14’ 15” E., at a depth of 140 fathoms, and Whitelegge 
has recorded the species from 50 fathoms in Botany Bay. 
Aegeon orientalis, Henderson. 
1893. <Aegeon ortentalis, Henderson, Trans. Linn. Soc., Zool. (2), V, p. 446, 
plexlihigs 16.7 
Three specimens in rather poor condition from the Persian 
Gulf and the Andamans evidently belong to this species, which 
does not appear to have been recognised since it was first described 
more than twenty years ago. 
The spinulation of the carapace agrees exactly with Hender- 
son’s description except that the serrations on the marginal carina 
vary in number from 7 tog. The abdominal sculpture also agrees 
with the original description ; but there are two longitudinal carinae 
on either side of the second abdominal somite, and the five carinae 
on the first somite, as well as the median carina on the second, end 
anteriorly in sharp spines. These spines were perhaps worn away 
in the type, which is larger than any of the three specimens here 
recorded. 
Although, as Henderson has remarked, the species bears a 
rather marked resemblance to A. caiaphractus, it is not in reality 
a very close ally of that species. As has already been pointed out 
it is intermediate in character between the more typical species 
and those that Alcock referred to the subgenus Parapontocanis. 
Pearson’s suggestion that A. orientalis is merely an extreme varia- 
tion of A. cataphractus! is certainly incorrect. A. ortentalis may 
readily be distinguished (i) by the complete absence of the hepatic 
groove, (ii) by the smaller number of serrations on the marginal 
carina of the carapace, (iii) by the sharp longitudinal lateral carinae 
of the first two abdominal somites and (iv) by the presence of only a 

! Pearson, Ceylon Pearl Oyster Fisheries, Macrura, p. 89 (1905). 
