170 Memoirs of the Indian Museum. [Vou. IV, 
tional groove, running almost longitudinally and situated midway between the lateral 
margin, and the commencement of the transverse groove. 
The presence of these grooves (see text-fig. 1), though the only constant charac- 
ter by which G. graphurus may be distinguished from its ally, is, I believe, a feature 
of sufficient importance to justify specific separation ; intermediate specimens appear 
to be wholly unknown. Pocock (1893, p. 475) notes that in a semi-larval form, 10 
mm. in length, the grooves are found only on the fifth abdominal somite, but that 
in all the other numerous examples which he examined, they were well-marked without 
sign of failing. 
Fig 1. 
Lrg. ran 
Fic. I. Gonodactylus graphurus 
Hie Gonoueconaeationans ; First five abdominal somites viewed laterally. 
A fine median carina is usually—perhaps invariably—found on the sixth abdo- 
minal somite, but this character is shared by some examples of G. glabrous. 
The other keels on the last abdominal somite and those on the telson appear’ to 
vary in precisely the same way as in the preceding species. In the two examples from 
Port Molle they are slender, but moderately swollen in the third specimen ; in all three 
the median and submedian keels of the telson terminate in spines. ; 
The colouring of living G. graphurus is doubtless as variable as that of its allies. 
There are only three specimens in the Indian Museum :— 
$356 
Australia. Queensland Museum. Id ,60 mm. 
$006 Port Molle, Queensland. Australian Museum. Id¢,I2, 35,40 mm. 
Both in Henderson’s experience and in my own, G. glabrous occurs on the coasts of 
India to the complete exclusion of G. graphurus, and it would naturally be expected 
that, in the case of the latter species, further indications of a geographical range more 
limited than that of G. glabrous would be found in the published records. It is not 
altogether clear, however, that this is so. The head-quarters of G. graphurus appear 
to lie in an area comprising Oceania, the N. coast of. Australia, Amboina and the China 
Seas, but from certain isolated records from the E. African coast, it would seem that the 
species is in reality distributed over the whole Indo-pacific region. 
As regards the African records it will be noticed that Nobili, writing towards the 
end of 1906, includes in his synonymy of G. glabrous, his record of G. graphurus from 
