TORNATELLID 4. 465 
Orper—OPISTHOBRANCHIATA, Milne-Edwards. 
Sus-orperR—THOTIBRANCHIATA, Cuvier. 
N.B.—The fossil Opisthobranchiata have lately received a large share of 
attention in M. Cossmann’s admirable work ‘ Hssais de Paléoconchologie comparée ’ 
(Premitre livraison, Fevrier, 1895); and still more recently in his splendid 
Monograph, ‘ Etudes sur les Gastropodes des Terrains Jurassiques,’ now in course 
of publication in the Memoirs of the Geological Society of France. This author 
greatly favours the subdivision of families and genera. Thus we find the 
following families enumerated from the Jurassic rocks,—Acteonide, Tornatinide, 
Bullide, Aceridze (nov. fam.), and Aplustride. M. Cossmann also includes 
Ceritella and Fibula amongst the Opisthobranchiata under Tubiferidee (nov. fam.). 
The genera and sections are also largely multiplied. Without in the slightest 
degree questioning the scientific value of these subdivisions, it is proposed to group 
the Opisthobranchiata of our Inferior Oolite, for present purposes, under the 
families Tornatellidee (Actezeonide) and Bullide. 
Family—TORNATELLIDAI (Actmonip2). 
Shell external, convoluted, ovoid, conoidal, spire depressed or prominent ; whorls 
tolerably numerous, without internal absorption, aperture entire, narrow.’’—FIscHER. 
N.B.—The following genera, subgenera, and sections of this family are 
recognised by M. Cossmann as occurring in the Inferior Oolite, viz. Tornatellea, 
Conrad (e.g. 7. pulchella, Deslong.); <Actxonina, d’Orbigny (e.g. A. gigantea, 
Deslong.) ; Striacteonina, nov. sect. (e.g. Act. Sarthacensis, d’Orb.). Cylindro- 
bullina, von Ammon (e.g. Act. Scarburgensis, Lycett; Cylindrites, Morris and 
Lycett (e. g. Actwon acutus, Sowerby). 
Trochacteonina, Meek, is also quoted from the Bathonian (e.g. Act. ventricosa, 
@Orbigny, and Cassis Esparcyensis, d Archiac). 
In the present instance it is proposed to retain the older generic classification 
of the Tornatellide of the Inferior Oolite, whilst indicating as far as possible the 
equivalents under the new system. For the most part the specimens are not 
sufficiently well-preserved to show the finer points. 
