OF MOLLUSCA. 219 



B. Lingual membrane none. Jaws none (p. 217). 

 Fam. XI. TETHYADiE. 



Body depressed. Mantle indistinct. Veil bearded on the edge, 

 very large, funnel-shaped. Tentacles two, dorsal ; branchial plumes 

 alternating with papillae along the back. Anus lateral, dorsal. Jaws 

 none. Lingual membrane none. 



1. Tethys. 



Body depressed. Mouth tubular, surrounded by a large funnel- 

 shaped veil, fringed on the edge. Tentacles two, retractile, lami- 

 nated ; sheath retractile. Foot large. Gills numerous, branched, 

 alternating with papillae on each side of the back. Teeth none. 

 Jaws none. Pelagic ; attached to floating plants. 



1. T. leporina, t. 210. f. 1, 2. 



Suborder IV. Cerabranchia. 



Gills on the upper surface of the mantle, fusiform, papillary, 

 simple or branched. 



A. Lingual membrane broad, with numerous longitudinal series of 

 teeth (p. 221). 



Reproductive organs with a single external orifice. Liver diffused, 

 and a single central gastro-hepatic vessel. The posterior vessel of 

 the gastro-hepatic system below the ovary. 



Fam. XII. DENDRONOTID.E. 



Frontal veil small. Tentacles two, dorsal, laminated and retrac- 

 tile within sheaths. Branchiae branched or papillose, in a single 

 series along the sides of the back. Vent lateral. Jaws distinct. 

 Lingual membrane broad, with many series of teeth. 



1. Dendronotus. 



Body compressed, elongate, prismatic. Mantle obsolete ; frontal 

 veil with branched appendages. Tentacles clavate, laminate, with 

 branched tubular sheath. Gills ramose, in a single series down each 

 side of the back. Foot linear. Lingual membrane rather narrow, 

 with several (10 * 1 * 10) series of teeth, the central broad, the lateral 

 narrow, all denticulated. 



1. D. arborescens, t. 212. f. 1, 6, t. 214. f. 4, t. 225. f. 1, t. 228. 



f. 2. Forbes fy Hartley, B.M. t. Z.Z. f. 5. 



2. D. pulchella, Alder Sf Hanc. Ann. Nat. Hist. ix. 33. 



3. D. felina, Alder ty Hanc. Ann. Nat. Hist. ix. 33. 



