BRITISH NUDIBKANCHIATE MOLLUSCA. 37 



Fam. 3. Eolidid^. Branchiae papillose or branched, arranged on the sides of the back ; 

 stomach branched. 

 Sub-Fam. Meliba>ina>. Tentacles 2, with sheaths. 



Dendronotus, Doto. 

 Sub-Fam. Eolidince. Tentacles without sheaths, 2, 4, or none. 

 Eolis, Pterochilus, Hermaea, Alderia, Proctonotus. 



Professor Allman, in his paper on the anatomy of Action,* proposed a modified arrange- 

 ment of the Nudibranchiate Mullusca, which we subjoin. 



Order 



a 



Section. Family. Genera. 



''Branchiae in the mesial line placed in a circle, ") 



more or less complete, round the anus, r Doris, Polycera, &c. 

 Liver compact 1 Dorididcs. ) 



Branchiae arranged along the sides or scattered. ) ^^ g ^ ThetiSt 

 Tritoniadce. ) 



/-Branchiae papillose, or branched, or muricated. ) Eolis, Alderia, Dendro- 

 Liver disintegrated ) Eolidid®. ) notus, Glaucus, &c. 



v Branchiae foliaceous. Actceonida. Actaeon, Placobranchus ? 



But the most extensive arrangement of the order yet published, is that of Dr. J. E. Gray, 

 in Mrs. Gray's ' Figures of Molluscous Animals.' In this work the distribution of the whole of 

 the known species into genera and families has been attempted. This, it must be 

 acknowledged, is a very difficult task, with the present imperfect descriptions of foreign 

 species ; and we do not think that, in all cases, Dr. Gray has succeeded in his details, but as 

 that distinguished naturalist has superseded this arrangement by another in a late number of 

 the 'Annals of Natural History/ f it is unnecessary to enter into any further description of it 

 on the present occasion. 



The classification now proposed by Dr. Gray, is founded upon the characters afforded by 

 the spines of the tongue taken in conjunction with the breathing organs, and is as follows : 



1. Gills surrounding the vent on the middle of the hinder part of the back. 



Fam. 1. ONCHiDORiDiE. Teeth 2 in each cross series; gills in separate cavities; mantle edging 

 the foot and simple. 



Acanthodoris, Onchidoris. 

 Fam. 2. DoBiDiD^:=Doridina and Polycerina, Gray. Teeth many in each cross series, sub- 

 similar, inner often smaller ; gills in a common cavity ; mantle edge simple. 

 a. Doris ; (3. Goniodoris, Ceratosoma ; y. Mgires. 

 Fam. 3. TRiopiD,E=Triopina, Gray. Teeth many (rarely only 4) in each cross series, inner 

 lateral ones large, irregular-shaped ; gills in a common cavity ; mantle small, edged 

 with tentacles. 



Triopa, Idalia. 



* Ann. Nat. Hist., v. 16, p. 145. f lb. 2d Ser., v. 11, p. 218. 



