208 MANUAL OF THE MOLLUSCA. 



Animal with 4 long tentacles, mantle with, a siphonal process ; foot ex- 

 panded, truncated in front, furnished with a float after the manner of 

 lanthina ; lingual dentition closely resembling Jeffrey sia. 



Distr. 2 sp. Taken in the towing-net oif C. Byron, E. coast Australia, 15 

 miles from shore; floating, and apparently gregarious. (J. Macgillivray.) 

 Mindoro. (Adams.) 



SECTION B. GYMNOSOMATA, Bl. 



Animal naked, without mantle or shell ; head distinct ; fins attached to 

 the sides of the neck ; gill indistinct. 



FAMILY III. 



Body fusiform; head with tentacles often supporting suckers; foot small, 

 but distinct, consisting of a central and posterior lobe ; heart opistho-bran- 

 chiate ; excretory orifices distant, on the right side ; lingual teeth (in Clio) 

 12.1.12, central wide, denticulated, unciui strongly hooked and recurved. 



CLIO (L.)* Miiller. 



Etijm. Clio, a sea-nymph. Syn. Clione, Pallas. 



Type, C. borealis, PI. XIV. fig. 45. (C. caudata, L. part.) 



Head with. 2 eye tubercles and 2 simple tentacula; mouth with lateral 

 lobes, each supporting 3 conical retractile processes, furnished with numerous 

 microscopic suckers ; fins ovate ; foot lobed. In swimming, the Clio brings 

 he ends of its fins almost in contact, first above and then below. (Scoresby.} 



Distr. 4 sp. Arctic and Antarctic Seas, Norway, India. 



Sab-genus ? Cliodita (fusiformis), Quoy and Gaimard. Head supported 

 on a narrow neck ; tentacles indistinct. 3 sp. Cape, Amboina. 



PNEUMODERMON, Cuvier. 



Etym. Pneumon, lung (or gill), derma, skin. 



Type, P. violaceum, PI. XIV. fig. 46. 



Body fusiform; head furnished with ocular tentacles; lingual teeth 

 4.0.4 ; mouth covered by a large hood supporting two small, simple, and two 

 large acetabuliferous tentacles, suckers numerous, pedicillate, neck rather 

 contracted ; fins rounded ; foot oval, with a pointed posterior lobe ; excretory 

 orifice situated near the posterior extremity of the body, which has small 

 branchial processes and a minute, rudimentary shell. 



* This name was employed by Linnaeus for all the Pteropoda then known ; his 

 definition is most suited to the "northern clio," probably the only species with which 

 he was personally acquainted. The first species enumerated in the Syst. Nat. is 

 C. caudata, and reference is made to an indeterminable figure in Brown's Jamaica, 

 and to Marten's account of the Spitzbergen mollusk (C. borealis.) In cases like 

 this the rule is to adopt the practice of the next succeeding naturalist who defines 

 the limits of the group more exactly. 



