60 



Transactions. — Zoology. 



CO. Posterior valve having a sinus behind, 

 without slits; girdle hairy or nude, 

 never scaly 

 BB. Surface of intermediate valves divided into a 

 narrow dorsal area and latero-pleural areas, 

 the latter formed by the union of the lateral 

 and the pleural areas ; valves more or less 

 covered by the naked spieulose or hairy 

 (never scaly) girdle. 

 C. Girdle provided with pores bearing tufts of 

 bristles 

 CC. Girdle spongy, produced forward 

 AAA. All valves or valves i. to vii. possessing insertion 

 plates cut into teeth by slits ; the teeth sharply 

 sculptured or "pectinated" outside by fine 

 vertical grooves. 

 B. Valves lacking eyes. 

 C. Girdle scaly . . 

 GO. Girdle leathery, with short bristles 

 BB. Valves having eyes ; posterior valve not 

 deeply sinused behind, its insertion plate 

 developed. Girdle covered with calcareous 

 spines or spinelets 

 BBB. Valves having eyes upon the lateral areas 

 and head-valve. Insertion plate of tail- 

 valve reduced to a smooth ledge or ridge, 

 having no posterior sinus. Girdle leathery, 

 microscopically velvety .. 



Plaxiphora. 



AcantJwchites. 

 Spongiochiton, 



Chiton. 

 EudoxocMton. 



Acanthopleura. 



Onithochiton. 



Genus Lepidopleurus, Eisso (1826). 



L. inquinatus, Reeve. 



Pilsbry, Man. Conch. (1), vol. xiv., p. 90, pi. xviii., figs. 49, 

 50. 



Genus Callochiton, Gray (1847). 



Key to Species. 



A. Entire surface delicately shagreened . . . . C. platessa. 



B. Central areas with elevated separate threads, parallel 



to jugum . . . . . . . . . . C. illuminatus. 



C. A row of deep longitudinal pits in front of lateral 



areas . . . . . . • . . . C. empleurus, 



C. platessa, Gould. 



Pilsbry, Man. Conch. (1), vol. xiv., p. 49, pi. x., figs. 1-5. 

 Crocinus, Reeve, and versicolor, A. Ad., are synonyms. 



C. illuminatus, Reeve. 



Pilsbry, Man. Conch. (1), vol. xiv., p. 51, pi. ix., figs. 92-94. 



C. empleurus, Hutton. 



Man. N.Z. Moll., p. 113. 



Genus Ischnochiton, Gray (1847). 



Key to Species. 



Scales of girdle faintly striated, mingled with non-striated 



scales . . . . . . . • . . ..I. longicymha. 



All scales of girdle deeply grooved, 3-4 grooves on a scale I. parkeri. 



