1896.] A. Alcock — CarcinologicaJ Fauna of India. 155 



Leach (Zool. Miscellany III. pp. 12-14, 1817), gave brief diagnoses of four 

 species of Matuta. One of these — M. banksii — I believe to apply to Rumph'a 

 Cancer lunaris. 



A second — If. lesuearii — is referred by Miers, and I think with justice, to the 

 if. victor of Fabricius. 



A third — If. peronii — is also, and I think rightly, referred by Miers to M. victor, 

 Fabr. 



The fourth — M. lunaris — is regarded by Miers, whose paper will be considered 

 in the sequel, as applicable to if. picta of Hess, a species characterized by having 

 a simple rostrum and a tubercle in the postero-lateral border. Now Leach's figure 

 shows a distinctly bilobed rostrum, and has no tubercle on the postero-lateral border, 

 so that I do not see how the name M. picta can apply to it. Leach's M. lunaris seems 

 to me rather to agree with the species described by Henderson as M. miersii. 



To sum up, it seems to me that three species were known to Leach, namely 

 If. banksii, Leach, (Rumph's species), M. victor Fabr. and perhaps the species now 

 known as If. miersii, Henders. 



The great naturalist Milne-Edwards only admitted two species of Matuta, 

 namely M. lunaris and M. victor, and it is only because I have been able to examine 

 over 400 specimens from all parts of the Indian coasts, that I venture to disagree 

 from him. 



I can reconcile his description of M. lunaris with the M. lunaris of Leach and 

 with Guerin's figure of M. peronii (not Leach's) ; but on the strength of Hilgendorf's 

 statements I do not see how it can be reconciled with Herbst's Cancer lunaris. 

 Milne-Edwards italicizes the fact that the carpus of the penultimate pair of legs is 

 bicarinate : now the only species known to me that agrees with his description in 

 other respects, and has also the carpus of the penultimate legs full and indistinctly 

 bicarinate, is Henderson's M. miersii. 



The M. victor of Milne-Edwards seems to be Fabricius' species, although I do 

 not think that the whole of the synonomy can be accepted. 



Miers' classical attempt (Trans. Linn. Soc. Zool. (2) I. 1875-79 [1877] p. 243) 

 to simplify the confusion existing in this group, although forming a careful critical 

 and extremely valuable paper, yet fails for the reason that the character selected 

 by Miers for the primary subdivision of the genus — namely the sculpture of the 

 hands and fingers — varies not only according to sex (as Miers indeed fully recog- 

 nized), but also according to age. 



In Miers' system the adult males of M. victor, Fabr. and of M. lunaris Hbst. 

 Hilgendorf, belong to one section of the genus, and the young males tq the other 

 section. 



One has, of course, to be very careful in deciding that any given small speci- 

 men of Matuta corresponds with the young of any given large specimen ; but when 

 one finds, for example, that a small male individual, taken on the same spot with a 

 large male and female, exactly resembles the adults in all important characters, and 

 differs from the adult male, and agrees with the adult female, just in those very 

 characters where the adult female differs from the adult male ; when, therefore, 

 such a young one can be confused with no other known species ; and when moreover 

 these agreements and differences are found to have a general correspondence 

 throughout the whole genus ; then one can with some confidence assign that young 

 individual to its place. 



One of the most constant differences, throughout the genus, between the adult 



