178 THE GASTROPODA 
rhinophores very long, non-retractile ; British. Ancula, Loven ; mantle 
border scarcely distinguishable, without appendages ; rhinophores branched ; 
British (Fig. 163). Doridwneulus, Sars. Lamellodoris, Alder and Han- 
cock, Ancylodoris, Dybowsky, the only freshwater Nudibranch, from Lake 
Baikal, probably belongs to this family. Faminy 3. H&TERODORIDIDAE, 
Fischer. No branchia. © Genus— Heterodoris, Verrill and Emerton. 
Faminty 4. Dortpipak, Gray. Mantle oval, covering the head and the 
greater part of the body ; anterior tentacles ill developed ; branchiae 
generally retractile. Genera—Hexabranchus, Ehrenberg ; branchiae made 
up of separate fascicles, retractile within distinct 
cavities. Doris, Linnaeus; mantle elliptical, 
covering the whole body; branchiae tri- or 
quadri-pennatifid ; British (Fig. 160, C). (Sub- 
genera— Archidoris, Bergh. Rostanga, Bergh. 
Aldisa, Bergh. Cadlina, Bergh. Jorunna, Bergh. 
Platydoris, Bergh). Chromodoris, Alder and 
Hancock ; body long and narrow ; foot longer 
than the mantle ; branchial plumes simply 
pinnate. Famity 5. Doripoprsipar, Alder. 
Pharynx suctorial; no radula; peri-branchial 
rosette on the dorsal surface, above the mantle 
border. Genus—Doridopsis, Alder and Hancock. 
Famity 6. CoRAMBIDAE, Bergh. Anus and 
eo branchia posterior below the mantle border. 
Pe i ne nea ah foot, Genus—Corambe, Bergh (Fig. 164). Famiy 7. 
g, pallial gills; m, mouth; pa, PHYLLIDIIDAE, Alder and Hancock. Pharynx 
mantle”; ¢, tentacle. (After : c ee 
H. Fischer.) suctorial ; branchiae surrounding the body and 
placed between the mantle and the foot. Genera 
—Phyllidea, Cuvier ; anus dorsal. Fryeria, Gray ; anus posterior between 
the mantle and the foot. 
The three last families constitute the sub-tribe ‘‘ Porostomata,” 
characterised by the reduction of the buccal bulb, which is transformed 
into a suctorial apparatus, ‘ 
Fic. 164, 
Tripe 3. EoLimpomorpP#a (= Cladohepatica). 
Nudibranchs in which the whole of the liver is contained in the 
integuments and the tegumentary papillae (Fig. 77). The genital duct 
is diaulic, and the male and female orifices are contiguous. A pair of 
laterally placed mandibles is present (Fig. 73, A). The anus is antero- 
lateral, except in the Proctonotidae, in which it is median. The tegu- 
mentary papillae are not ramified: they frequently contain terminal sacs 
(enidosacs), which communicate on the one hand with the exterior, on the 
other hand with the digestive canal (Fig. 165). The cnidosacs contain 
nematocysts, which according to Wright and to Grosvenor are derived 
from the various species of Hydroids on which the animals feed. The 
nematocysts are invaginated while they are in the cnidosacs, but when 
expelled from them they are evaginated (Fig. 166). In some species of 
Hedyle and Pseudovermis, in which there are no tegumentary papillae, 
