548 COLLECTIONS ntOM THE WESTEEN INBIAlf OCEAN. 



Tiis species is distuiguislied from the three others of the genus 

 by its much less distinctly trilobate front. P. tridentata, Miers, 

 •which is its nearest ally in this genus, has a much more coarsely 

 punctulated carapace, and differs in other characters. 



Three small male specimens of a species of Leueosia from the 

 Gulf of Suez {R. MacAndrew) in the Museum collection, which were 

 not described when I published my memoir on this group in 1877*, 

 because I doubted if they presented the characters of the fuUy adult, 

 bear a curious resemblance to this species. They are distinguished 

 not only by possessing a distinct, although shallow and imperfectly 

 defined thoracic sinus, but also by the absence of the lines of 

 granules from the inferior margin of the palm of the chelipedes 

 and from the margins of the outer maxillipedes. 



69. Nursilia dentata, Bell. 



A male was obtained at the Seychelles, 4-12 fins. (No. 194). 

 The wide Oriental distribution of this species, which has been 

 already noticed in the earlier part of this Eeport (p. 253), is evidenced 

 by the acquisition of this specimen. 



70. Arcania trndecimspinosa. 



Arcania undecimspinosa, De Haan, Faun. Japan. Crust, p. 135, 

 pi. xxiiii. %. 8 (1841) ; Bdl, Trans. lAnn. Soc. xxi. p. 309 (1856) ; 

 Cat. Uucos. Brit. Mus. p. 21 (1855). 



Arcania granulosa, Miers, Trans. Linn. Soc. ser. 2, Zool. p. 240, 

 pi. xxxviii. fig. 29 (1877) ; Proc. Zool. Soc. p. 44 (1879). 



Seychelles, 4-12 fins. (No. 194) ; an adult male. 



This specimen scarcely differs from De Haan's iigure and the 

 specimen from Moreton Bay in the British-Museum collection, which 

 I formerly separated on insufficient grounds under the name of 

 A. granulosa, except in its somewhat less strongly granulated 

 carapace and the slightly recurved lateral spines of the third pair. 

 Unfortunately the three posterior spines of the carapace were (sub- 

 sequent to ite examination) accidentally crushed in the specimen 

 from the Seychelles. 



• There is in the collection another male specimen from the 

 Seychelles (4^12 fms.), apparently referable to this genus, but 

 which I hesitate to separate as a distinct species, as, on account of 

 its very small size, I think it may not present all the characters of 

 the ftdly-grown animal. The carapace is nearly circular in outline 

 and is covered with close-set granules ; its lateral and posterior 

 margins are armed with twelve smaU. nearly equidistant and equal 

 granulated spines, those on the posterior margin being smaller and 

 tuberculiform. The front is bUobate and slightly concave above ; 



* Trans. Linn. Soc. ser. 2, Zool. i. p. 235 (1877). 



