i6 

 FaM. : CORYSTIDAE. 



Gen. : Nautilocorystes, Milne-Edwards. 



1829. Corystes (part) Latreille, Le Regne Animal, Cuvier, 



nouv. ed., v. 4, p. =^7^. 

 1833. Dicera (not Germar, 181 7) de Haan, Siebold's Fauna 



Japonica, Crustacea, pp. 4, 14 (see also pp. 112, 



xvi, xxviii, and mouth-organs t. A). 

 1837. Nautilocorystes^ Milne-Edwards, Histoire Naturelle des 



Crustaces, v. 2, p. 149. 

 1843. Dicera, Krauss, Die siidafrikanischen Crustaceen, p. 27. 

 1853. Dicera^ Dana, U.S. Exploring Expedition, v. 13, p. 298. 

 1893. Nautilocorystes, Stebbing, History of Crustacea, 



P- 74-75- 

 1899. Nautilocorystes, Alcock, Journ. Asiatic Society of 

 Bengal, v. 68, pt. 2, p. 104. 



Like Corystes in general form and in the arrangement of 

 the second antennae for forming an antennal tube, but 

 distinguished from it by two salient features, the third 

 maxillipeds having the fourth joint decidedly shorter instead 

 of longer than the third, with the fifth inserted not below but 

 on the apex, and the last trunk-leg having the terminal joint 

 flatly expanded with convex inner margin instead of being 

 narrow with inner margin straight. The five-jointed pleon 

 of the male is rather longer than in Corystes, the composite 

 segment not deeply notched. The second and third trunk- 

 legs have the terminal joint compressed as in the fifth pair, 

 but less expanded, only the fourth pair being narrow, with 

 triangular section ; in all the apex is acute. 



To the above characters de Haan adds that the buccal area 

 is oblong, narrower in front ; outer plates of first maxillipeds 

 above the middle incurved, narrow, on the inner margin 

 truncate, ciliated, at the apex acute, peduncles of the palps 

 surpassing the length of the outer plates, the flagella short ; 

 peduncles of palps of the second maxillipeds shorter than the 

 maxillae (but in Corystes longer). 



The importance of the antennal tube in the Corystidae is 

 clearly explained by Mr. Walter Garstang in the Journal of the 

 Marine Biological Association, N.S., v. 4, No. 3, pp. 22^,-22,2. 

 The animal deeply burrowing in the sand, with only the tips of 

 its long antennae above it, is no longer in a position to breathe 

 in the ordinary way by allowing the water to enter its 

 branchial chamber beneath the branchiostegite, and after 

 bathing the gills to pass out by the apertures at the side of 

 the mouth. It, therefore, reverses the current, allowing the 

 water to pass down the tube formed by the juxtaposed hairy 

 antennae and after serving the two branchial chambers to 

 make its exit by the usual doors of entrance. 



