396 DE. J. G. DE MAN ON CEUSTACEA CHIEFLY 



are furnished on their lower surface with a row of setae, of which the first are little 

 shorter than these joints, whereas the following regularly decrease in length towards the 

 tips ; the outer surface of the meri of these legs is distiactly granulated near the upper 

 and lower borders. The upper surface of the ambulatory legs is covered, the dactyli 

 excepted, with the same dark brown tomentum that one observes also on the side-walls of 

 the carapace and near the lateral margins of the upper surface ; the lateral margins of 

 these legs are furnished with somewhat longer setae. 



Eggs numerous, globular, small. 



The upper surface of the carapace has a very pale ochraceous colour. 



On the legs of the fifth pair several pedunculated Infusorige were attached. 



The genus Tritodynamia, Ortm., is apparently most closely related ; its chief difference 

 is probably presented by the external maxillipeds, the merus-joint of which is longer 

 than broad and not shorter than the ischium, and furthermore by the insertion of the 

 terminal joint on the inner border of the penultimate. The latter character was observed 

 by Nobili in a new species referred by him to Tritodynamia ; but it is still unknown 

 whether this character occurs also in the typical species, Trit. japonica, because the 

 outer footjaws of Ortmann's single specimen were much damaged. Probably, therefore, 

 the genus Tritodynamia ought to be referred to the subfamily Jsthenognathince (confer 

 Alcock, in Journ. Asiat. Soc. Bengal, vol. Ixix. part ii. 1900, p. 29i). 



Geographical Distribution. — East coast of Nippon, 38° N. lat., on a sandy bottom 

 {Stimpson). 



TRIGONOPLAX, H. M.-Edw. 



TiiiGONOPLAX UNGUiFORMis (de Haan). 



Ocypode [Elamene] wnguiformis, de Haan, Fauna Japonica, Crust. 1839, p. 75, tab. 2'J. fig. 1, (J ? , and 



tab. H. 

 Elamena (Trigonoplax) ungtdformis, Alcock, iu Journ. Asiat. Soc. Bengal, vol. Ixix. pt. ii. 1900, 



p. 387. 



One male, collected in deep water. Inland Sea of Japan. 



H. Milne-Edwards, in Annales Sciences Nat. 3" serie, Zool. t. xx. 1853, p. 224, 

 describes this species as having the carapace " arrondie en arriere et tres-deprimee." 

 These words are not quite exact, but liable to be misunderstood. The carapace, 

 measured from the rather obtuse tip of the triangular front to the middle of the 

 concave posterior margin of the carapace appears to be 7*4 mm. long; the greatest 

 breadth above the insertion of the third pair of legs measures 9*4i mm. The undivided, 

 smooth, and glabrous upper surface cannot be said to be " tres-deprimee " ; in a lateral 

 view of the carapace the middle part of the upper surface corresponding to the cardiac 

 area appears, indeed, to slope slightly downwards towards the front and more rapidly 

 towards the posterior and the slightly carinate antero-lateral margins. The postero- 

 lateral margins and the concave posterior border are distinctly lamellar. 



The legs of the second and third pairs are five times as long as the length of the 

 carapace without the front ; the upper border of the meri terminates in a small tooth. 



