434 NUDIBRANCHIATA 



Hexahranchus, Archidoris (Fig. 289), Discodoris, Dimihila, 



Cadlina, Centrodoris, Platydoris, Cliro- 

 modims, Miamira, with iiiaiiy .sub- 

 genera. 



Fam. 2. Doo'iojysidac. — Branchia and 

 rliinophores as in Dorididae, oral aper- 

 ture pore-shaped, suctorial, no radula. 

 Single genus, Doriopsis. 



Fam. ?). Phyllidiidae. — Body oval, 



depressed, leathery, a ring of branchial 



lamellae, only interrupted by the head 



and genital papilla, under the pallial 



^ ^^ «dge, oral aperture pore -shaped, suc- 



FiG. 289.— Z)om (^'-c/'w^oris) torial, no radula. Genera: PhylUdia, 



tubercuiata L., Britain : a, Frijcria. Bcrgh unites this and the 



anus ; br, brauchiae sur- o ^^ ■ ^ -n 



rounding the auus ; m, male preceding laniily lu the group Forosto- 

 organ ; /A, rA, rhiuophores. :,,^^^f^^^ which, with Fam. 1, form the 



group Dorididae cryi^tohranchiatae. 



Fam. 4. Polyccridae. — Body slug-like, branchiae not retractile, 

 usually surrounding the anus, rhinophores foliate, tentacles 

 simple, radula variable, central tooth generally wanting. Genera : 

 Notodoris, Triopella, Aegircs, Trio^Ki, Issa, Triopha, Crimora, 

 Thecacera, Polycerclla, Palio, Polycera, OJiola, Trevelyana, Nem- 

 hrotha, Uuplocamus, Plocamopherus, Kalinga. 



Fam. 5. Goniodoridae. — Body oval, depressed, branchia multi- 

 foliate, usually disposed in shape of a horse-shoe, rhinophores 

 foliate, retractile or not, mouth with a large suctorial proboscis, 

 radula variable. Genera : Akiodoris, Doridunculus, Acanthodoris, 

 Adalaria, Lamellidoris, Calycidoris, Goiiiodoris, Idalia, Ancula, 

 Drcpania. 



Fam. 6. Coramhidac- — Body otherwise Doris-like, but with 

 two posterior branchiae under the mantle edge, jaws present, no 

 central tooth, about five laterals. Single genus, Coramhe ( = 

 Hypohranchiaea). Bergh unites this and the two preceding 

 families in the group Dorididae phatierohranchiatae. 



Sub-order IV. Pteropoda. — The Pteropoda are pelagic 

 animals in which the lateral portions of the foot are modified 

 into fins, which are innervated by the pedal ganglia. Their 

 systematic position has undergone recent revision. It has been 

 the custom to regard them as an Order of equivalent value to the 



