320 PLEUROTOMARIID^. 



whorl. At the place where this is deflected there is an elongated, 

 kidney-shaped perforation surrounded by somewhat thickened 

 margins ; another small perforation is found about the centre of 

 the basis, but in the outer lip it is likewise surrounded with a 

 raised margin. 



? Brilonella, Kayser. 



Distr. — B. serpens, Kayser. Devonian ; Germany. 



Last whorl unwound and deflected upwards, so that the mouth 

 lays upon the top of the spire ; otherwise like Pleurotomaria. 



Obontomaria, Roemer. 

 Distr. — 0. elephantina^^oem&r. Devonian; Eifel. 

 Shell not spiral, extended-tubular, somewhat curved ; mouth 

 with slit terminating an external band. 



Troohotoma, Lycett. 



EtyTHi. — Trochus, and tome, a notch. 



Syn. — Ditremaria, d'Orb. Rimulus, d'Orb. 



Distr. — Fossil, 10 sp. Lias to Coral Rag ; Britain, France, 

 etc. T. Humhertina, d'Orb. (Ixxxii, 90). 



Shell trochiform, slightly concave beneath ; whorls flat, spirally 

 striated, rounded at the outer angles ; lip with a single per- 

 foration near the margin. 



Temnotropis, Laube. 



Distr. — T. carmaius, Groldfuss. Trias; St. Cassian. 



Shell ear-shaped, with rapidly enlarging keeled whorls, and a 

 very large oval aperture ; outer lip sharp with a deep slit, ter- 

 minating a slit-band on the keel. 



Ditremaria, Deslongc. 



Distr. — 2 sp. Grreat Oolite and Coral Rag ; France and 

 Germany. D. quinquecincta, Zlet. (Ixxxii, 91). 



Shell trochiform ; in place of the slit of Trochotoma, there 

 are two elongated oval holes united by a transverse fissure ; the 

 base of the shell presents a large callosity, the umbilicus is deeply 

 excavated, and a round tubercle arises from it ; the aperture is 

 contracted, and the upper angle of each lip bears a more or less 

 distinct tooth. 



ScHisMOPE, Jeffreys, 1856. 



Etym. — Schisme, a slit, and ope, a hole. 



Syn. — Woodwardia, Fischer, 1861. 



Distr.— isp. Mediterranean, Japan. Fossil, 1 sp. Miocene; 

 Bordeaux. 



Shell like Scissurella, but the spire is laterally compressed, as 

 in Stomatia, and is not so trochiform. The slit in the peristome 



