444 MOLLUSCA 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, 

Fic. 802. 5 Fic. 803. 
Pleurotomaria (Leptomaria) macromphala, Zittel. Tithonian; Stram- “§Porcellia Puzosi, Leveillé. Car- 
berg, Moravia. boniferous ; Tournay, Belgium. 
with band replaced by a row of perforations, of which the posterior ones are succes- 
sively closed. Carboniferous. 
Ditremaria, VOrb. (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. Cantantostoma, Sandb. 
Devonian. 

Fic. S05. 

A, Murchisonia bilineata, d Arch. and 
Vern. Devonian; Paffrath, near Cologne. 
B, M. Blumi, Wlipstein. Trias ; St. Cassian, 

i. 804. Tyrol. C, M. subsuleata, de Kon. Carbon- 
Ditremaria granulifera, Zittel. Upper Tithon- iferous ; Tournay, Belgium. Last two 
ian ; Stramberg, Moravia. whorls, 2/. 
Murchisonia, V 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 ; Lophospira, Whitf. ; Goniostropha, Oehlert ; Cheilotoma, 
Koken. 
Family 3. Bellerophontidae. M‘Coy. 
Shell bilaterally symmetrical, coiled in one plane, usually quite thick, with weakly 
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. 
