182 A. Alcock— Cctrcinological Fauna of India. [No. 2, 
The abdomen in both sexes is seven-jointed, the abdominal terga, 
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 male 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 Miers r 
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, Miers, 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 proa- 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 flagella exposed and visible at the sides of the rostrum. 
Meius of the exterior maxillipedes elongated, and articulated with the 
