GASTEROPODA. 



23 



bears a row of spines, which in the neighbourhood of the 

 aperture are tubular and have their ends perforated. The 

 o'enus ranges from the Devonian to the Jurassic. 



Fig. 407. — Pliorus canaliculatus. Cretaceous. 



In accordance with the views now most generally accepted, 

 we must also place here the important and widely-distributed 

 Palaeozoic genus UuoDvphalus, with its allies. 



Fig. 40S. — Cirrus Goldfussi. Devonian. 



The genus Euomphalus (figs. 409, 410) is entirely extinct, 

 and is essentially PalaBOzoic, ranging from the Silurian to the 



Fig. 409. — Euomphalus De-Ccwi (Billings), a, Front %'iew ; b, View of the umbilicus. 

 Devonian. 



Trias, but being most abundant in the Carboniferous rocks. 

 The shell in this genus is depressed or discoidal, the whorls 



