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laterally and as broad as the first, but much longer; the following segments increase in length 

 gradually; the terminal segment is elongate, only half as broad at the base as the penultimate 

 segment, and twice as long as broad. 



The present species has been first recorded from Ceylon (Gulf of Manaar); afterwards 

 it was obtained in the Gulf of Siam. The "Siboga" specimen is somewhat larger than those 

 previously known. 



Dimensions in mm. : 



Fronto-orbital distance 4. — 



Anterior margin of front 1.55 



Greatest breadth of carapace . . . 7.6 



Length of carapace 5.5 



Notonyx A. Milne-Edwards. 

 1873. Notonyx A. Milne- Edwards. Nouv. Arch. Mus. Paris, t. 9, p. 268. 



The carapace in this genus is almost entirely hairless, the fronto-orbital distance is wide 

 and nearly equals the greatest width of the carapace, the piriform eye-stalks present minute, 

 though quite distinct, eyes, and the walking legs are elongate, and, like the carapace, almost 

 devoid of hairs. 



The eye-peduncles are movable, not firmly fixed within the orbits, and this character, 

 which refutes the name Rhizopinae, has long been considered the exclusive possession of the 

 present genus; we now know, however, that movable eye-stalks occur in some other genera: 

 Paranotonyx Nobili, Chasmocarcinus Rathbun, Sehvynia Borradaile and in a new genus, allied 

 to the latter, which I propose to call Paraselwynia. 



A diagnosis of the present genus is given by Miers ^) and Alcock "). 

 Key to the species : 

 Breadth of carapace about 1.3 — 1.5 times its length, postero- 

 lateral margins slightly concave and somewhat convergent 

 backward. Inner angle of wrist of cheliped produced, turned 

 forward. Abdomen of cf broadly triangular, with the third 



segment broadest, and thence rapidly tapering N. nitidiis A. Milne-Edwards 



Breadth of carapace only about 1.2 times its length, postero- 

 lateral margins parallel. Inner angle of wrist of cheliped blunt, 

 not prominent. Abdomen of cT oblong, scarcely narrowed 

 towards terminal segment, with the third segment scarcely 

 broader than the second . A^. vitreus Alcock. 



I. Notonyx nitidus A. Milne-Edwards. 



1873. Notonyx nitidus A. Milne-Edwards. Nouv. Arch. Mus. Paris, t. 9, p. 269, pi. 12, f. 3. 



1886. Notonyx nitidus Miers. Rep. "Challenger", Brachyura, p. 236. 



1900. Notonyx nitidus Alcock. Journ. As. Soc. Bengal, v. 69, prt 2, p. 319. 



1) Rep. "Challenger", Biachyura, 1886, p. 235. 



2) Journ. As. Soc. Bengal, v. 69, prt 2, 1900, p. 318. 



71 



