ISCHNOCHITON. 109 



7-1 0, central valves 1 slit. Teeth acute ; eaves moderate ; sinus 

 wide, flat. Girdle furnished with very close, deeply striated, flat- 

 tened scales. Length 10, width 5 mill. ; divergence 95. 



Guadaloupe (Mus. Cuming, No. 44). 



One specimen is of a pale yellowish tint slightly variegated with a 

 brighter color ; another is more ashy and with the variegations of 

 pale olive. It has stronger sculpture than I. cdribbceorum, the 

 rugulse rising up like close rungs in a rope-ladder, and dentating 

 the sutures. (Cpr.) 



The above description, from Carpenter's MS. defines a form 

 which will probably prove to be a variety of /. caribbceorum, with 

 which species Carpenter, at a later date, united it. 



I. PRUINOSUS Gould. PI. 21, figs. 27, 28. 



Shell small, elongated, nearly elliptical, convexly elevated, sub- 

 carinate, or rather somewhat doubly carinate along the back ; sur- 

 face generally covered with microscopic punctures, arranged in 

 lozenge. Lateral areas very slightly raised, and longitudinally 

 imbricate-sulcate ; central areas with faint lines of growth and 

 punctures in quincunx ; anterior valve concentrically striate, not 

 punctate ; posterior valve slightly umbonate, and crossed by a 

 transverse ridge, behind which it is concentrically striate. It is 

 frosted or mottled with dark brown, ash, purple, green, &c. Mar- 

 gin minutely granulated, so as to look hoary. (Old.*) 



"Some specimens are of a uniform pale green. Margin clouded 

 with dark green ; some had two or three distinct, white blotches on 

 the sixth valve, the rest of the shell being olive-green, with a line 

 of faint green along middle of back ; another had the ground-colour 

 a clear olive, three dark brown spots bordered with white on each 

 side of posterior margin of valves, a row of similar spots surround- 

 ing the terminal valves just above insertion, and the whole surface 

 sparsely and irregularly spotted in the same way, so as to present a 

 delicately mottled aspect. A fourth variety was of a uniform dark 

 rose-color, and the margin clouded with dark red bands. Inter- 

 nally it was dark red or rosy along the middle, and dull yellow 

 towards the sides. All the other varieties were of a pale greenish 

 hue internally." (Couth, in Old.') 



Length 17-1, breadth 8| mill. 



Off Fort Santa Cruz, Rio Janeiro, on stones in 2 or 3 fms. 



