104 ISCHNOCHITON. 



/- 



The pricked interstices between the close-set ridges which consti- 

 tute one of the distinguishing features of this species are scarcely 

 discernible without the lens. (Rve.) 



Simon'* Bay, Cape of Good Hope. 



C. pertmm RVE., Conch. Icon. pi. xvi, f. 88 (1847). Ixchnochi- 

 ton pertusus CPR., MS. 



Carpenter's notes from two specimens in the Cuming collection 

 are as follows : The figure in Reeve does not represent it well. It 

 is one of the rissoi group. Shell much arched, elevated, but the 

 jugum rather blunt. Umbo of posterior valve raised, situated at 

 the anterior third ; the slope behind it very slightly concave, nearly 

 straight. Girdle with Ischnoid scales, but small, long, somewhat 

 imbricating and striated. Color olivaceous, variegated. Jugal 

 area not defined from the central areas, which are sculptured with 

 very numerous and fine rather blunt lirulse with extremely small 

 interstices ; or the surface might be described as finely grooved. 

 These small riblets are longitudinal, very slightly granose, and at 

 the diagonal border of the lateral areas become rugulose, passing 

 on to join with the riblets of the latter. The lateral areas have 

 about 9 to 12 very fine radiating riblets which are made granose by 

 the longitudinal riblets from the central areas crossing them. The 

 end valves have very close and regular radiating rows of grains, the 

 sculpture being very like that of catenulatus, but in that species the 

 concentric wrinkles predominate. The head valve has 12 slits, 

 median 1, posterior valve 9 slits. Teeth quite sharp, with long pro- 

 jecting eaves, which are not spongy. Sinus broad, rather deep, flat, 

 smooth, but deeply channelled on each side at the inner bases of the 

 sutural plates. Terminal valves stained with brownish-purple inside. 

 ' Length 32, breadth 16 1 mill. ; divergence 113. 



I. ERYTHRONOTUS C. B. Adams. Unfigured. 



Shell small, subelongate, [convex, not carinated] ; yellow-white, 

 [the back] irregularly maculated with red ; lateral areas ribbed, the 

 ribs nodulous; dorsal areas [sulcate-] striated; girdle scaly [yel- 

 lowish-white, maculated with ashen]. Length 13J, width 7 2, mill. 



Jamaica (Adams) ; St. Thomas and Porto Rico (Blauner). 

 Chiton erythronotus C. B. AD., Proc. Bost. Soc. N. H. 1845, p. 9. 

 0. (Ischnochiton') erythronotus SHUTTLW., Bern. Mittheil. 1853, 

 p. 76. 



