CRASPEDOCHITON. 285 



The representation of the coarse pores of the eaves in fig. 28 

 causes the teeth to appear pectinated, which is by no means the case. 



Var. pseudorissoi Cpr. Teeth of insertion hardly thickened at the 

 edges ; mucro subraedian ; girdle scales elongated, flattened, 

 striated. 



Malta. 



The type is no. 51 of Mus. Cuming. Carpenter, after examining 

 more material, decided that this form was specifically identical 

 with the Ch. polii Phil. His type specimen is a young shell. Not 

 having seen it, I am unable to tell whether all of the scales, or only 

 those at the edge are elongated. In either case the subgeneric name 

 Beania or Beanella falls as a synonym. 



Genus XXV. CRASPEDOCHITON Shuttleworth, 1853. 



Oraspedochiton SHUTTLEW., Bern. Mittheil. 1853, p. 67. Type 

 Ch. laqueatus. 



Valves exposed, slightly immersed, granulated ; with five low ribs 

 on the head-valve ; insertion plates sharp-edged ; those of anterior 

 valve long, strongly grooved inside and out, having slits at the 

 positions of the external ribs ; median valves having the insertion 

 plates thin, sharp, 1-slit; posterior valve with subcentral mucro, 

 teeth short, grooved. Girdle corneous, very minutely roughened. 



The characters of eaves and sinus are unknown to me. The 

 external sculpture reminds one of Nuttallina, which differs in the 

 posterior inucro, etc. The sharp-edged insertion plates, and the 

 correspondence of slits to external ribs show clearly that this genus 

 does not belong in the neigborhood of Chiton, Tonicia, etc., where 

 Carpenter placed it, but with the genera here accompanying it 

 which share these peculiarities. 



C. LAQUEATUS Sowerby. PI. 39, figs. 42-51 ; pi. 44, fig. 68. 



Shell ovate, depressed, granulated ; pale, tawny or greenish, 

 maculated with purple or green ; the dorsal rib purple. 



Anterior valve having five low ribs, median valves squared at 

 the ends, and having the sculpture often worn from the median 

 ridge, which is wedge-shaped on each valve, the wedge being com- 

 posed of about six truncated, somewhat wedged segments, and on 

 each side there are oblique, irregular ridges. Posterior valve having 

 the mucro central and very little raised. 



