82 BULLETIN OF THE 



Triforis torticulus n. s. 



Shell having much the habit of T. biyemma Watson, but attaining a much 

 larger size, and devoid of the brown tinge ; specimens in hand decapitated, 

 waxen yellowish white, about six whorls in length, and if perfect, according to 

 the proportions of T. bigemma, would probably attain over an inch in length 

 and perhaps eighteen whorls ; it is possible that the apex may be blunt, in 

 which case the length and number of whorls might be less ; shell very gradu- 

 ally tapering, subcylindrical, sinistral, with rather inflated whorls bevelled to- 

 wards the suture ; longitudinal sculpture consisting, on the posterior surface 

 of the whorls, of four principal spiral ridges continuous, on the later whorls, 

 over the transverse furrows though considerably indented by them, but, on the 

 earlier whorls, entirely cut through by the furrows, and therefore appearing as 

 nodules on the transverse ridges ; the anterior spiral ridge forms an exception to 

 this, it is everywhere continuous as a simple thread behind the suture, which 

 is appiessed against it ; beginning with this, which is the least conspicuous of 

 the four, it is separated from the next posterior spiral by a well-defined gutter ; 

 the next spiral is quite close to it, and the third is nearly in the middle of the 

 whorl ; the second and third are conspicuously larger than the others and nearly 

 equal in size, the space between them is about equal to their breadth singly ; 

 the fourth ridge is smaller and less conspicuous, and the space between it 

 and the third spiral is twice the width of the latter, sloping rather rapidly 

 toward the suture, which is immediately behind the fourth ridge, appresaed 

 against the first ridge of the whorl behind ; the second and third ridges are 

 sharp on the edge, falling abruptly on the posterior side and rounded toward 

 the basal side, but the fourth is an evenly rounded thread ; between this and 

 the third on the later whorls is a very delicate thread, while spiral stria 1 are 

 visible here and there under a powerful glass ; the first ridge forms the pe- 

 riphery of the (in the adult) somewhat flattened base, on which appear, toward 

 the periphery, one or two faint spiral threads or grooves, which in the young 

 an- quite pronounced ; transverse sculpture consisting of about twenty-seven 

 distinct riblets, separated by about equal furrows, slightly flexuous over the 

 inflated whorls, but in general parallel with the axis of the shell ; these are 

 marked by rather prominent parallel lines of growth, which pass over the 

 periphery, and are distinct on the base ; columella twisted, Blender, Blightly 

 thickened ; anterior canal slender, small, somewhat produced and bent to the 

 right ; aperture rounded, not completely developed in the specimena at hand. 

 Length of lour whorla in a nearly adult specimen, HMS j in a younger one, 

 en. Breadth of the former shell behind, 4.0; in Front, 42; of the latter 

 shell behind. 2.6 ; in front, 2.5. Length of last whorl in the fizsl mentioned, 

 5.0 ; of aperture, -2.^:> ; width of the same, 1.87 mm. 



Yucatan Strait, 640 bis. 



This form seems nearest to T. bigtmma of any described Bpecies, but. so ht 

 as the specimens in hand go, seems quite sufficiently distinguished from it. 



When perfect and adult, it must be a very line example of the genus, ami one 



of the largest known. 



