1909.] CRUSTACEA FROM CHRISTMAS ISLAND. 713 



perceptible approximation to T. styx as compared with Miers's 

 type specimens. The long, straight, rosti'al spines, divergent from 

 the base, and the more numerous and longer spines on the legs, 

 are characters which seem to justify the separation of the species. 

 I do not find, however, that the carapace is " much narrower " 

 than in T. styx, and the rostral spines are not always more than 

 half the length of the carapace. Dr. Andrews's collection includes 

 some males in the breeding phase, with enlai'ged chelse and widely 

 gaping fingers. 



Perinea tumida Dana. 



Perinea tumida Dana, Crust. U.S. Expl. Exp. i. p. 114, pi. iv. 

 figs, la-/ (1855); Rathbun, Bull. U.S. Fish Comm. for 1903, 

 pt. iii. p. 881 (1906). 



Paratho'e rotundata Miers, Ann. Mag. Nat. Hist. (5) iv. p. 16, 

 pi. V. figs. 2, 2 a (1879) ; Haswell, Oat. Austral. Crust, p. 30 (1882) ; 

 Klunzinger, Spitz- und Spitzmundkrabben des Eoten Meeres, 

 p. 45, pi. i. figs. 1 a-d, text-fig. 10 (1906). 



About 18 specimens of a little crab collected by Dr. Andrews 

 are identical with the types of Miers's Paratho'e rotundata from 

 Port Curtis and Fiji. The rostral teeth, although short, are much 

 more prominent than in Miers's figures and are separated by 

 a rounded notch, and there is a small tooth at the distal end of 

 the basal segment of the antenna unnoticed by Miers. 



There can be little doubt, however, that Miers's genus and 

 species are synonymous with those of Dana, quoted above. By 

 the courtesy of Miss Rathbun I have been able to examine a 

 specimen from Laysan recorded by her [l. c.) as Perinea tumida 

 Dana. It is a large male in which, as in the large female from 

 the Gulf of Suez mentioned by Miers, the tubercles on the cara- 

 pace are rather less prominent than in smaller specimens, but it 

 undoubtedly belongs to the same species. In addition to the 

 difi'erences from Dana's account mentioned by Miss Rathbun, it is 

 to be noted that the rostral teeth are much less prominent than in 

 the original figures and the notch between them is rounded instead 

 of angular. The tooth at the end of the basal segment of the 

 antennules is also less prominent. I see no reason, however, to 

 dispute Miss Rathbun's identification of the Laysan specimen with 

 Dana's species and if this be accepted the name given by Miers 

 must be placed as a synonym. 



EXPLANATION OF PLATE LXXII. 



Fig. 1. Iiioxantliodes alcoeki, g. et sp. n. Female, dorsal view. X 9. 



2. „ „ Anterior part of bod}', ventral view. X 18. 



3. „ „ Larger cliela of male, from outer side. 



4. Sesanna murrayi, sp. n. Male, dorsal view. X 6. 



5. „ „ Upper surface of chela. 



6. Syastenus andreiosi, sp. n. Male, dorsal view. X 3. 



7. „ , , Orbital region from below. 



8. Hyastenus imcifer, sp. n. Female, dorsal view. X 3. 



9. „ „ Dactj'lus of leg of last pair. 



