i6o Memoirs of the Indian Museum. [Voi<. 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. chiragra 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. Lanchester'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 

 cases 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. 1 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' 2 are indicated 

 in the table on p. 159. The largest examples are males, 105 mm. in length. The 



1 See addendum, p. 198. 



2 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. 



