OF MOLLUSCA. 21/ 



1. DlPHYLLIDIA. 



Cloak exposing the head, coriaceous. Tentacles laminated, lon- 

 gitudinally approximated, partially retractile within a common cavity. 

 Veil reflected. Branchiae of two kinds, the anterior longitudinally 

 folded, the posterior transversely. Tongue broad, with numerous 

 longitudinal series of simple lateral teeth, and a denticulated central 

 tooth. Jaws horny. 



1. D. lineata, t. 204. f. 1, t. 205. f. 1, 2, 3, 4 ; Forbes fy Hartley, 



B.M.t. K.K.K. f. 1. 



2. D. verrucosa, t. 205. f. 6. 



3. D. ocellata, t. 205. f. 5. 



4. D. pustulosa, t. 204. f. 2. 



" Central tooth of Diphyllidia lineata wide, convex in front, exca- 

 vated behind at the base and produced on both sides ; cutting edge 

 with one sharp point, left side smoothish, right side crested and den- 

 ticulated ; lateral teeth 30, claw-like, serrated on the lower margin 

 (fig. 118)."— Loven. 



Fig. 118. — Teeth of Diphyllidia lineata. 



Lingual membrane of Diphyllidia lineata broad, folded in the 

 middle, rounded in front. Teeth 30 ■ 1 * 30 ; central broad, convex 

 in front, hinder base excavated and produced on each side, one- 

 cuspid, each side finely denticulated ; lateral claw-like, uniform, equal, 

 thick, apex attenuated, lower edge crenulated. Jaws two, horny, 

 similar. 



Suborder III. Polybranchia. 

 Gills on the upper surface of the mantle, lamellar or plumose. 



A. Tongue-membrane broad, with many longitudinal series of teeth , 

 forming oblique cross rows (p. 219). 



Fam. IX. TRITONIAME. 



Body subquadrilateral. Cloak small. Veil large, projecting in 

 front of the head. Liver central. Gills on the sides of the back, 

 lamellar, arranged on the pallial ridge. Teeth in many (21 or 29) 

 longitudinal series. Tentacula two, retractile within the sheath. 

 Vent lateral. Jaws horny, large. 



1. Trttonia. 



Body prismatic, often thick and firm. Head with digitated veil. 

 Tentacles two, ramose, filamentous, retractile within the plain tubular 



