178 COSTELLARIA. 



T. CATENATA, Swainson, PI. 53, fig. 515. 



White, "with large irregnhir ehestmit-bvown sfjots. mrangtHl in 



bands. Length, "5 inch. 



hU of Aiittmt, Polynesia. 



An obscure shell, probably not adult. 

 T. LiLACiNA, Sowb. PL 53, fig. 51(i. 



Shell finel}' decussated; ash color, lightt'r at the suture. 



Length, '6 inch. 



ILthitat II II /ill 11 in /I. 

 T. MARMOREA, A. Ad. PI. 53, figs. 517, 518. 



Olivaceous, marked with reddish brown ; longitudinally costate, 

 costas thick, subnodose above, interstices with revolving striii?. 



Length. -5 inch. 



Isle of Negros, PJdUpinms ; coarse sand, ten iatlioms. 



Sowerby's two illustrations, the only figures of this species 

 heretofore published, and which I copy, appear to represent two 

 different species. 



T. Arracanensis, Sowb. PI. 53, figs. 5UI. 

 Brown, with a median white line, ribs lighter colored. 



Length, -65 inch. 



Arnifdii. 

 T. CREBRILIRATA, Rceve. PI. 53, figs. 521-526, 530. 



Light cliestnut or olive, tops of ribs lighter, with usually a 

 narrow central brown band, and a superior white line ; ribs 

 narrow, interstices with close revolving strije. 



Length, l-25-l'75 inches. 



Indian Ocean; Japan ; Philippines ; Polynesia. 



Reeve hesitated to describe this as a distinct species from his 

 M. polifa, to which, he says, it bears the same relation that the 

 ribbed does to the smootli A^ariety of M. ehenus-, I venture, 

 nevertheless, to locate the two species in distinct groups. 1 do 

 this, whilst expecting that Reeve's suspicion of their ideutity 

 will be confirmed, as it is a case paralleled by many others in 

 this genus, all pointing to the evanescent nature of the sculpture 

 and patterns of coloring. In fact, unless Ave set uj) an artificial 

 standard for the separation of species, in some genera, Ave should 

 haA'B no species remaining, to speak of. T. ro.sea, Kiener, not 

 Duclos (fig. 522), T. teymilirata^ Sowl>. (fig. 523), T. ruhricata, 

 Ree\'e (fig. 524), T. subtruncata, SowT). (fig. 525), T. Layardi^ 



