174 A. Alcock — Carcinological Fauna of India. [No. 2, 



Oreophorus, Bell, Trans. Linn. Soc. Vol. XXI. 1855, p. 306, and Cat. Leucos. 

 Brit. Mns. p. 18. 



Carapace broadly semi-elliptical or subpentagonal, so that its 

 postero-lateral margins overhang and completely conceal the legs in 

 flexion (much as in Calappa) ; strongly convex, nodose, and often sym- 

 metrically eroded or honey-combed. The front forms a distinct, slightly 

 upturned, triangular projection, with the orbits almost on its under 

 surface. 



Eyes small ; orbits quite complete, the inner canthus being com- 

 pletely closed by the tight-fitting basal antennal joint. No antennary 

 flagella. Antennules folding obliquely. 



The external maxillipeds close the buccal cavern completely : their 

 exopodite is narrow, with the outer edge almost straight : the triangu- 

 lar merus is nearly two-thirds the length of the ischium, measured 

 along the inner border. 



Chelipeds massive, not very much longer than the carapace : hand 

 short and broad : fingers about twice as long as the hand, their inner 

 surface hollowed like a spoon : the immobile finger enormously 

 massive. 



True legs small, and hidden, when flexed, by the lateral expansions 

 of the carapace. 



The abdomen of the male consists of three pieces, and is acutely 

 triangular ; that of the female consists of four pieces. 



In India these little crabs are found only on bottoms of dead coral shingle, to 

 the eroded fragments of which the crabs themselves have a most extraordinary 

 likeness, the likeness being increased by an encrusting growth of Foraminifera, 

 Polyzoa, etc., to which the crabs like the shingle, are subject. 



18. Oreophorus reticulatus, Adams & White. 



Oreophorus reticulatus, Adams and White, ' Samarang ' Crustacea, p. 54, pi. vi. 

 fig. 1 (1850) : Bell, Trans. Linn. Soc. Vol. XXI. 1855, p. 307, and Cat, Leucos. Brit. 

 Mus. p. 19 : A. Milne-Edwards, Ann. Soc. Ent. Franc. (4) V. 1865, p. 151 : Miers, 

 Zool. H. M. S. ' Alert,' pp. 185, 254 : A. 0. Walker, Journ. Linn. Soc, Zool., XX. . 

 1890, p. 111. 



Carapace with three caverns, diminishing in size from before back- 

 wards, excavated just inside the front and lateral margins on either 

 side. The caverns have undermined edges, and the first communicates 

 with the second by a tunnel, while the second may sometimes (young) 

 have an open communication with the third, and sometimes (adults) 

 only the remains of a communication. 



The intestinal region and the true posterior margin are insolated 

 from the rest of the carapace by an undermined channel, which sends 

 forwards a short branch on either side of the cardiac region. The 



