444 



MOLLUSGA 



SUB-KINGDOM VI 



plane. Outer lip sharp, with long slit. Slit-band prominent, traversing the central 

 portion of the whorls. Devonian and Carboniferous. 



Kokenella, Kittl. Very flat, discoidal, and only slightly asymmetrical, with a 



broad slit -band. Trias. 

 K. Fischeri, Hoernes sp. 

 Polytremaria, de 

 Kon. Shell turbinate, 



FIG. 802. 



Pleurotomaria (Leptomaria) macromphala, Zittel. Tithonian ; Stram- 

 berg, Moravia. 



FIG. 803. 



Porcellia Puzosi, Leveille. Car- 

 boniferous ; Tournay, Belgium. 



with band replaced by a row of perforations, of which the posterior ones are succes- 

 sively closed. Carboniferous. 



JDitremaria, d'Orb. (Fig. 804). Two oval perforations connected by a slit are 

 present behind the outer lip ; base with an umbilical callus. Jura. 



Trochotoma, Deslongch. Shell turbinate, with conical base. A slit closed at 

 either end is present behind the outer lip, 

 and corresponding to it is a slit -band. 

 Trias and Jura. 



Schizogonium, Koken ; Temnotropis, 

 Laube. Trias. Gantantostoma, Sandb. 

 Devonian. 



FIG. 804. 



Ditremnria gmnulifera, Zittel. Upper Tithon- 

 ian ; Stramberg, Moravia. 



FIG. 805. 



A, Murchisonia Ulineata, d'Arch. and 

 Vern. Devonian ; Paffrath, near Cologne. 

 , M. Blumi, Klipstein. Trias ; St. Cassian, 

 Tyrol. C, M. subsukata, de Kon. Carbon- 

 iferous ; Tournay, Belgium. Last two 

 whorls, 2/ lt 



Murchisonia, d'Arch. and Vern. (Fig. 805). Shell turreted, with numerous smooth 

 or ornamented whorls. Outer lip with a slit, and corresponding to it a slit-band. 

 Cambrian to Trias. Maximum distribution in Devonian and Carboniferous. 



Sub-genera : Hormotoma, Salter ; LopTiospira, Whitf. ; Goniostropha, Oehlert ; Cheilotoma, 

 Koken. 



Family 3. Bellerophontidae. M'Coy. 



Shell bilaterally symmetrical, coiled in one plane, usually quite thick, with iveakly 

 developed nacreous layer. Aperture broad, oval, or narrowly elongate. Outer lip with a 

 notch or slit in the middle, corresponding to which is often a band or row of perforations 

 along the whorls. Cambrian to Trias. 



The Bellerophontidae were classed by Montfort with the Cephalopoda, by Deshayes, 

 on account of their resemblance to Atlanta, with the Heteropoda, and by de Koninck 

 with the Aspidobranchiates. The thick shells sometimes retain traces of their 

 original pigmentation. At least 300 Palaeozoic species have been described. 



