284 Carcinological Fauna of India. 



subfamily (Macrophthahninse) is a thin plate. The front is usually of no 

 great breadth, and is often a narrow lobe more or less deflexed. The 

 orbits occupy the whole anterior border of the carapace outside the 

 front, and their outer wall (between the far ends of the upper and 

 lower borders) is often defective. The buccal cavern is usually large 

 and a little naiTower in front than behind, the external maxillipeds 

 are foliaceous and usually completely close it, but if they do not they 

 never leave between them a wide rhomboidal space exposing the 

 mandibles. The abdomen of the male is narrow. Male openings 

 sternal. 



Family Pinnoterid^. Small crabs, usually living as commensals 

 in the mantle-cavity of Bivalve MoUusks or Ascidians, in the cloaca of 

 Holothurians, in worm-tubes, or in coral-stocks, and hence often 

 exhibiting degeneration of some of the organs of special sense. The 

 external maxillipeds vary : the merus, though often very large, is never 

 quadrilateral, and never carries the palp distinctly at the antero- 

 internal angle : the ischium is often small, and is sometimes absent or 

 indistinguishably fused with the merus, in which case the merus lies 

 with its long axis directed obliquely or almost transversely inwards : 

 the exognath is small and more or less concealed. The interantennular 

 septum, when distinguishable, is a thin plate. [The front is narrow, 

 the eyes and orbits very small, the corneae sometimes obsolescent : 

 the antennules and antennae are usually very small and cramped. The 

 buccal cavern is short and of great breadth, being commonly semi- 

 circular in outline. The male abdomen is very narrow]. Male 

 openings sternal. 



^ rj n^ Family MicttridjE. Amphibious Catometopes resembling the 



n( OcypodidsR in habits. The buccal cavern is of enormous size and is 



completely closed by the enormous foliaceous convex external maxil- 

 lipeds, whose coarse palp articulates with the antero-external angle 

 of the merus, and whose short slender exognath is entirely concealed 

 and carries no flagellum. The interantennular septum is narrow. 

 The orbits are represented by a small post-ocular spine, the eyes being 

 quite unconcealed. [Carapace elongate-globose : front a narrow decli- , 

 vous lobe : the rudimentary antennular flagella fold nearly vertically, 

 and are a good deal concealed by the front : the abdomen of the male 

 resembles that of the female and covers the greater part of the sternum. 

 No membranous spaces {tympana) on the meropodites of the legs or on 

 the sternum]. Male openings sternal. 

 626 



