160 Memoirs of the Indian Museum. [Vou. IV, 
numerous than any other form and comprises the vast majority of large specimens. 
From the fact that it is connected by numerous intermediates with practically every 
other type, it may be suggested that this is the starting-point from which the others 
have diverged; on the other hand it may be argued that A is a specialized type that has 
become more or less isolated in such localities as the Andamans, Cocos Is., and the 
Persian Gulf—the only places from which any considerable number of specimens have 
been examined. Before any definite conclusions on this point can be reached, data 
supplied by large collections from other localities are necessary. 
As regards evidence of isolation among other varieties, it will be noted that A 
seems to be entirely absent from the Ceylon Coast. Only a few specimens are available 
and most of these were obtained on the Pearl Banks where G. chivagra seems to occur 
sparingly in company with large numbers of G. glabrous. None of the specimens are 
large ; the majority belong to D (= ‘ smithi’), while some, all very young, are referred 
to H. Further material is necessary before any decided opinion can be formed, but 
there appears to be some indication that D represents a small race that exists in this 
locality to the exclusion of the more generally abundant form A. lLanchester’s work 
seems also to suggest that this type prevails at Male Atoll in the Maldives, but the 
number of recorded specimens is again very small. 
From the figures given it will be seen that males and females occur in equal pro- 
portions, and that there is no trace of any correlation between sex and varietal form. 
The colouring of this species in life appears to be fully as variable as the detailed 
structure of its telson. Among the limited number of fresh specimens that have been 
examined, the general tone was in some cases yellow, in others dull orange, brick red or 
olivaceous brown. Numerous other shades doubtless occur and occasional reference 
to them is found in the literature ; it may well be that colour changes due to environ- 
ment, and possibly to other factors, still remain to be discovered. Males are in most 
sases very darkly coloured on the ventral surface and in this respect differ strikingly 
from females which are invariably pale beneath. 
That G. chiragra is capable of making a loud snapping noise there can be little 
doubt, but the means by which this is effected has not, so far as I am aware, been 
determined.'! It is possibly caused by snapping the fingers as in many Alpheidae, but 
it may perhaps be due merely to striking stones on other surrounding objects with its 
prehensile claws. Annesley (1866, p. 338), who succeeded in keeping a specimen alive 
for more than a month, notes that it made a loud sound by knocking its claws against 
the glass in which it was confined, but the noise was produced quite inadvertently when 
the animal was engaged in attacking an ophiuroid. 
Annesley found that his specimen fed voraciously on actinians. 
The localities from which the specimens examined were obtained’ are indicated 
in the table on p.159. The largest examples are males, 105 mm. in length. The 
1 See addendum, p. 198. 
» The majority of these specimens are from the Indian Museum collection, but others, which were 
kindly sent me for examination by Prof. Kishinouye, Mr. J. C. Moulton and Dr. J. Pearson, are included. 
