70 CH^TOPLEURA. 



and segmentata Rve.). — Helioradsia Thiele, t. c, p. 385 (H. gemma 

 Carp.). 



The valves are solid, porcellanous within, having rather long sharp 

 teeth and squared sinus. Externally they are. sculptured with longita- 

 dinal headed rlblets on the central areas, and pustules or pustulose 

 ribs on the lateral areas. Mucro in front of the middle. Girdle 

 having corneous hairs, sometimes rising from a dense mass of chaffy 

 scales. 



Chcetopleura is closely allied to Pallochiton in sculpture and valve 

 structure generally, but Pallochiton has the mucro far to the rear. 

 Thiele has subdivided the genus, but his divisions are based upon 

 trivial features of the radula, which characterize single species or 

 groups of species of less systematic rank than the assemblages called 

 ** sections" in the present work. 



The species, although few in number, are found in most warm and 

 temperate seas. 



C. HENNAHi var. JASPIDEA Gould. PL 10, figs. 29, 30. 



Shell broad-ovate, thin and light, somewhat strongly carinated ; 

 under a magnifier it is found to be everywhere punctured in quincunx. 

 It is generally dark liver-red clouded with longitudinal pencillings 

 of more or less deep rose red colors ; central areas closely and 

 minutely marked with granulated, longitudinal lines ; lateral areas 

 small, distinguished by their greater smoothness, and having four or 

 five rather imperfect granular lines upon them ; terminal valves with 

 radiating lines of distant granules, the posterior one excavated and 

 with a transverse ridge, and strongly marked with the lines of 

 growth. Margin coriaceous, covered with short hoary down. 

 (Gld.) 



Callao. 



Chiton jaspideus Gould, Proc. Bost. Soc. Nat. Hist, ii, p. 143, 

 July, 1846 ; Expedition Shells, and Otia Conch, p. 4 ; U. S. Expl. 

 Exped., p. 325, atlas f. 414, 414a. — Chmtopleura jaspidea Thiele, 

 Das Gebiss d. Schn. ii, p. 380, t. 31, f. 12 (dentition.) 



This is probably a mere form or variety of C. hennahi, distin- 

 guished by the greater prominence of the pustules upon the lateral 

 areas. 



C. ASPERRiMA (Couthouy) Gld. PI. 14, figs. 1, 2. 



Shell elongated-oval, narrowed anteriorly, moderately convex, sub- 

 carinate, brownish-olive along the back, with a lilac bloom at the 



