80 TROCHUS. 



formed of two ridges close together, the interstices bearing numerous 

 fine spiral strire and sharp microscopic incremental striee ; base con- 

 vex, concentrically sculptured with numerous (6 to 9) smooth stride, 

 in the intervals between which very numerous microscopic striulse 

 revolve ; aperture rounded, oblique, outer and basal margins thick- 

 ened and very minutely crenulated within ; columella oblique not 

 tortuous above, nor entering the umbilicus, but inserted upon its 

 side; front edge nearly straight, denticulate at the base; umbilicus 

 wide, not very deep, its margin somewhat denticulate. 

 Alt. 7, diam. 10 mill. 



S. Australia ; Tasmania. 



T. plebejus Phil. Zeitschr. f. M'd. 1851, p. 41, and Conchyl. C-ib. 

 p. 326, t. 46, f. 10.— Fischer, Coq. Viv., p. 243, t. 83, f 2, 2a.— 

 Clanculus nodiliratus A. Adams, P. Z. S. 1851, p. 163. — -C. nodolir- 

 atus Tenison-Woods, Proc. Roy. Soc. Tasmania, 1877, p. 40. 



Both Adams and Philippi proposed names for this form in 1851. 

 I give precedence to that of the latter author because the description 

 is better, and is accompanied by excellent figures. The species 

 when typically developed is easily recognized by the very coarse 

 sculpture of the upper surface, and the minute concentric striation 

 of the base and interstices. To this (typical) form Dr. Fischer gave 

 the mss. name T. muscarius, which he considers a var. /?. of plebejus. 

 There are also smoother forms exhibitingnumerous lir?e above, which, 

 Avhile still unequal in size, are not nearly so prominent as in the 

 types. These specimens (pi. 13, figs. 77, 78) have a rounded pe- 

 riphery, and only the upper few lirjeare granulose. In the Academy 

 collection they are marked C. ruhicundus Mighels ; but I have seen 

 no description of such a species by that author. The ground color 

 is yellowish, obliquely, narrowly radiate above and below with 

 blackish lines, edged anteriorly with white, the lines of base and top 

 uniting in a V-shaped angle on the periphery, when the pattern is, 

 not too much interrupted. 



T. BiCARiNATUS Angas. PI. 11, figs. 33. 



Shell umbilicated, turbinate, solid, very dark purplish-brown ; 

 whorls 6, prominently keeled in the center, the last whorl with two 

 keels, one above and one below the j^eriphery, sculptured all over 

 with distinct separated rows of regular, close-set bead-like nodules, 

 those on the keels being double the size of those between them, the 

 interstices crossed with fine oblique strife ; outer lip strongly dentate 



