188 MANUAL OF THE MOLLUSCA. 



small lobed veil ; dorsal tentacles ear-shaped, with large plicated cavities at 

 their bases ; eyes small, sessile between the tentacles ; mantle not extending 

 beyond the shell ; gill forming a series of plumes beneath the shell in front 

 and on the right side; reproductive organ in front of the dorsal tentacles; 

 excretory orifice posterior, tubular. 



Distr. 3 sp. Canaries, Medit. India, China, Sandwich Ids. 



Fossil 2 sp. Eocene . U. States, Sicily. 



TYLODINA, Rafinesque. 



Type, T. punctulata, Raf. ( = citrina, Joannis) 3 sp. Medit. Norway. 



Shell limpet-like, depressed, apex sub-central, with a minute spiral nucleus. 



Animal oblong, foot truncated in front, rather pointed behind; dorsal 

 tentacles ear-like, with eyes sessile at their inner bases ; oral tentacles broad ; 

 branchial plume projecting posteriorly on the right side. 



FAMILY V. PHYLLIDIAD^E. 



Animal shell-less, covered by a mantle, branchial laminse arranged in 

 series on both sides of the body, between the foot and mantle. Sexes united. 



PHYLLIDIA, Cuvier. 



Type, P. pustulosa, Cuv. Etym. Diminutive of Phyllon, a leaf. 



Animal oblong, covered with a coriaceous tuberculated mantle ; dorsal 

 tentacles clavate, retractile into cavities near the front of the mantle ; mouth 

 with two tentacles ; foot broadly oval ; gills forming a series of laminse ex- 

 tending the entire length of both sides ; excretory orifice in the middle line, 

 near the posterior end of the back, or between the mantle and foot ; repro- 

 ductive organs on the right side ; stomach simple, membranous. 



Distr. 4 sp. Medit. Red Sea, India. 



DTPHYLLIDIA, Cuvier. 



Type, D. Brugmansii, Cuv. Syn. Pleurophyllidia, Chiaje. Linguella, Bl. 



Animal oblong, fleshy ; mantle ample ; gills limited to the hinder two- 

 thirds of the body ; head with minute tentacles and a lobe-like veil ; vent at 

 the right side, behind the reproductive orifices; lingual teeth 30.1.30. 



Distr. 4 sp. Norway, Brit. (D. lineata, Otto) Medit. 



SECTION B. NUDIBEANCHIATA. 



Animal destitute of a shell except in the embryo state ; branchiae always 

 external, on the back or sides of the body ; sexes united. 



The Nudibranchiate sea- slugs are found on all coasts where the bottom is 

 firm or rocky, from, between tide-marks to a depth of 50 fathoms; a few 

 species are pelagic, crawling on the stems and fronds of floating sea-weed. 

 They have been found by MiddendorflP, in the Icy Sea, at Sitka, and in the 

 sea of Ochotsk ; in the tropical and southern seas they are abundant. No 



