TROCHOMORPHA. 131 



T. ZENOBIA Pfeiffer. PL 42, figs. 14, 15, 16. 



Shell depressed, rather solid, opaque, tawny-brown, paler around 

 the umbilicus, shining. Umbilicus deep, showing all the whorls, 

 one-sixth the greater diameter of the shell. 



Spire conoidal, apex obtuse. Earlier 2 whorls convex, shining, 

 the following whorls slightly flattened above the suture, slowly 

 increasing, closely and strongly plicatulate-striate, the strise arcuate ; 

 last whorl convex above, acutely carinated ; the base convex, shin- 

 ing, having light, arcuate growth strise ; no spiral lines either above 

 or below. Aperture oblique, subrhombic, flesh-colored within ; 

 upper lip arcuate and arched forward ; basal lip well arched, thick- 

 ened, the columellar lip somewhat more strongly arcuate and pro- 

 duced forward toward its insertion. 



Alt. 11-11 J, greater diam. 24, lesser 21 J mill. ; greatest width of 

 aperture 11 mill. 



Alt. 10, greater diam. 23, lesser 20 mill. 



New Georgia, Solomon Is. 



H. zenobia PFR., P. Z. S., 1863, p. 527 ; Monogr. v. p. 250. 



This hitherto unfigured species is well distinguished by the stria- 

 tion of the upper surface, which is uncommonly strong and regular 

 for a Trochomorpha. The shell figured is from the A. D. Brown 

 collection (in Mus. Acad. Nat. Sci.) ; but we have also examined 

 specimens in the exhibition series of the Academy, and from the 

 collection of Mr. J. Ritchie, Jr., of Boston, the measurements last 

 given above being taken from a shell in the Ritchie collection. 

 Except in size the species varies but little. 



T. CONVEXA Hartman. PI. 30, figs. 20-25. 



Shell umbilicated, the umbilicus deep and narrow, its width con- 

 tained 6J times in the diameter of the base ; conoid-trochiform, the 

 base rather flattened, periphery very acutely carinated. Base and 

 carina and suture chestnut-brown, upper surface corneous-brown, 

 becoming lighter above. Surface having delicate but obvious 

 growth strise. 



Spire conoidal, its outlines convex ; apex obtuse ; suture hardly 

 impressed. Whorls 6, very slowly widening, the last not descend- 

 ing, acutely keeled, slightly concave below the keel, then becoming 

 gently convex, and passing suddenly into the umbilicus which is 

 deep and straight-sided like a well. Aperture subrhombic, oblique^ 

 the lip thin and sharp ; upper lip slightly arched forward, basal lip 



