CRUSTACEA. 251 



The larger specimen closely resembled the specimens referred to 

 M. affirm in the Museum collection, and scarcely differs from M. mam- 

 millaris except in the (relatively) somewhat longer, more acute 

 median spine of the posterior margin, and shorter chelipedes ; and 1 

 think it probable that a larger series would demonstrate the necessity 

 of uniting the two species. The younger examples may be distin- 

 guished from those referred to M. australis by their narrower cara- 

 pace, and the longer, more acute, and non-recurved posterior marginal 

 spines. 



100. Myra mammiUaris, Bell. 



An adult male is in the collection from Port Denison, 4 fms. 

 (No. 111). 



There are in the Museum coUection specimens from Adelaide, 

 S. Australia (purchased), and others without special locality. 



lOl.'Myra australis, HaswelU 



Myra mammillaris (young), Miers, Tram. Linn. Soc. ser 2, Zool. i. 



p. 2-39, pi. xxxviii. figs. 25-27 (1877). 

 ? Myra australis, HasweU, Proe. lAfm. Soc. iV. S. W. iv. p. 60, pi. v. 



fig. 3 (1880) ; Catalogue, p. 122 (1882). 



Three specimens are referred doubtfully to this form from Port 

 Molle, 14 fms. (No. 93), and one from Port Denison, 4 fms. (No. 122) 

 (first collection); also a male from Thursday Island, 3-4 fms. 

 (No. 177), two females from the same locality, 4-5 fms. (No. 165), 

 (to the back of one of which is attached a fine specimen of a species 

 of Acetabularia), and two males from Prince of Wales Channel, 

 obtained at 7 fms. (No. 142) and 9 fms. (No. 157). 



In some of the specimens I have examined the carapace is much 

 more evenly granulated than in others, and they also differ in the 

 more or less recurved posterior median spine and the greater or 

 lesser dilatation of the intestinal region ; in some females the post- 

 abdomen is comparatively narrow, whereas in others it covers the 

 whole of the sternal surface. Although some of the larger spe- 

 cimens approach nearly in their characters to M. mammillaris, yet, 

 as all may be distinguished by their more orbiculate carapace, more 

 aoutely-angulated pterygostomian regions, the more or less recurved 

 posterior median spine, and relatively shorter chelipedes, I prefer to 

 adopt fori them, at least provisionally, Mr. HasweU's specific name. 

 I should add, however, that in Mr. HasweU's figure the male post- 

 abdomen is represented as shorter than in our specimens, with the 

 sides somewhat constricted at base of the terminal segment. 



There are specimens from Shark Bay, West Australia, in the 

 Museum collection (H.M.S. 'Herald') which probably belong here, 

 but in. one (a female) the granulations of the carapace axe very 

 indistinct. 



