182 Carcinological Fauna of India. 



The abdomen in both sexes is seven-jointed, the abdominal terga r 

 like the thoracic sterna, bearing a few spines or tubercles. The epimeral 

 plates corresponding to the third and fourth trunk legs are also 

 spinate. 



Andaman Sea, 130-405 fathoms. 



A large mnle of this fine species have been figured for "Illustra- 

 tions of the Zoology of the ' Investigator' " for 1896. 



Note on some obvious growth-changes in Plafcymaia wyville-thomsoni. 



In very young specimens (carapace less than half an inch in 

 diameter) the whole carapace is closely and sharply spiny. 



In larger specimens (carapace about three-quarters of an inch in 

 diameter) the carapace has become closely and finely granular, with the 

 spines persistent only in definite situations, somewhat as in MieiV 

 figure and description (loc. cit.) 



In larger specimens (carapace two and a half inches in diameter) 

 the carapace has become coarsely and bluntly granular, without any 

 spines, except a few quite anteriorly in the neighbourhood of the 

 hepatic region. 



In the largest specimens (carapace three to nearly four inches in 

 diameter) the carapace is in places quite smooth, the only spines present 

 being two external to the eye, and one on the front margin of the 

 hepatic region. 



In contrast with the carapace, the spines on the abdominal sterna 

 of the male show no signs of effacement with age. 



The colours also vary with age. In young males the carapace is 

 red, with or without white points, and the legs are red and white in 

 alternate bands. In the adult the colour is uniform. 



Oncinopus, de Haan. 



Oncinopus, de Haan, Fauna Japonica, Crust., p. 87. 



Oncinopus, Miera, Journ. Linn. Soc, Zool., Vol. XIV. 1879, p. 645 ; and ' Challen- 

 ger' Brachyura, p. 20. 



" Carapace semi-membranaceous, elongate, narrow-triangulate and 

 depressed. Rostrum very short, composed of two vertically compressed 

 laminiform lobes : no pra3- or post-ocular spines. Post-abdomen in both 

 sexes distinctly seven-jointed. Eyes slender and projecting laterally. 

 Antennae with the basal joint very short and slender, and not attaining 

 the front, the fiagella exposed and visible at the sides of the rostrum. 

 Merus of the exterior maxillipedes elongated, and articulated with the 



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