THE GASTROPODA 



177 



TRIBE 2. DORIDOMORPHA. 



Nudibranchia with external symmetry, in consequence of the median 

 position of the anus, which is posterior and generally dorsal, and sur- 

 rounded by ramified pallial appendages constituting a secondary branchia 

 (Fig. 162, g). The liver is not ramified in the integuments. The genital 

 duct triaulic. Spicules present in the mantle. 



FAMILY 1. POLYCERATIDAE, Abraham. A more or less prominent 

 frontal veil ; branchiae non-retractile. Genera Euplocamus, Philippi 

 (Fig. 162) ; ramified dorsal appendages on the border of the mantle. 



FIG. 162. 







Euplocamus eroceux, dorsal aspect. 

 ((, anus ; /, foot ; fr.a, frontal append- 

 ages ; g, gill ; pa.a, pallial appendages ; 

 rh, rhinophore. (After Vayssiere.) 



FIG. 163. 



Ancula cristata, dorsal view, a, 

 anus ; br, pallial gill encircling the 

 anus (external to these respiratory 

 appendages are seen ten other club- 

 like pallial appendages); t, posterior 

 (branched) cephalic tentacle or rhino- 

 phore. (From Lankester, after Alder 

 and Hancock.) 



Polycera, Cuvier ; the mantle border bears on each side a single posterior 

 pointed appendage ; British. Thecacera, Johnston ; the mantle border 

 with club-shaped appendages ; the branchia formed of three lobes directed 

 forwards ; British. Aegirus, Loven ; body tuberculate ; rhinophores not 

 lamellar ; a dorsal mandible ; British. Plocamopherus, Leuckart. Palio, 

 Gray. Cnmora, Alder and Hancock. Triopa, Johnston, British. Trio- 

 pella, Sars. FAMILY 2. GONIODORIDIDAE, Adams. Mantle border pro- 

 jecting ; frontal veil reduced and often covered by the anterior border of 

 the mantle. Genera Goniodoris, Forbes ; frontal veil not continuous 

 with the mantle ; mantle quadrangular and incised posteriorly ; British. 

 Acantkodoris, Gray ; mantle oval, papillate ; rhinophores retractile ; British. 

 Idali<(, Leuckart ; mantle reduced and fringed with long appendages ; 



