WEST AMERICAN PYRAMIDELLID MOLLUSKS. 103 



costal spaces as wide as the ribs, crossed by subequal, irregularly 

 spaced, raised threads, the posterior one of which forms quite a cord 

 at the summit of the whorls; this is followed by a rather wide pit; 

 then two closely spaced, raised threads; another pit equal to the 

 first; then six very fine closely spaced threads; a third pit equal to 

 the others; two strong threads, followed by a peripheral pit. 

 Periphery of the last whorl well rounded. Base rather prolonged, 

 well rounded, marked by tlie continuation of the axial ribs, which 

 extend to the umbilical area and eight spiral threads. Aperture 

 oval; posterior angle acute; outer lip tliin; columella slightly curved; 

 parietal wall covered by a faint callus. 



Two specimens were obtained ofT Spondylus, at Mazatlan, Mexico, 

 one a young individual, the other an adult; the latter is on tablet 

 1986, Liverpool collection, British Museum. It has eight post- 

 nuclear whorls, and measures: Length 3.8 mm., diameter L2 mm. 



TURBONILLA (PYRGISCUSj CORA D'Orbigny. 



Chemnitzia cora D'ORBUiXY, Voy. Am. Merid., vol. 5, 1847, p. 398, pi. 76, figs. 7-9- 



"Shell elongate-conic, thick, ornamented longitudinally by very 

 deep folds, between which are fine, regular spiral striations, among 

 which four are deeper, three of which reproduce themselves in very 

 regular manner on all the whorls. Nucleus very large, oblong; spire 

 elongate-conic, composed of eight flattened whorls which are sepa- 

 rated by a very marked suture; aperture oval; lip thin; color wliite. 

 Long. 5 mm., diam. L5 mm." 



To the above diagnosis he adds: "Ornamented with ribs and trans- 

 verse striae, like C. ornata, this is larger in proportion, and is remark- 

 able in that four of the striae are more profoundly traced than the 

 others and reproduce themselves on all the whorls of the spire." 



It inhabits the coast of Peru near Payta. We have not seen any 

 specimens belonging to this species, and have translated the above 

 from the original description by D' Orbigny. 



The figures referred to do not depict the specimen described. 

 They represent a short, stout individual having six post-nuclear 

 whorls of a light brown color, with about 12 strong axial ribs on the 

 first, 18 on the fourth, and 20 on the penultimate whorl; and instead 

 of four (three between the sutures) spiral lines the figure shows 

 seven between the sutures and about an equal number on the base. 

 D'Orbigny carefully points out that C. cora has only three strong 

 spiral lines visible between the sutures, and compares it with C. ornata. 

 We therefore are inclined to believe that some mistake has been made 

 in the figures. The wrong specimen may have been figured or the 

 artist may have figured C. cora wrongly. 



