A Manual of Elementary Geology / or, The Ancient Changes of the Earth and its Inhabitants as Illustrated by Geological Monuments

by Sir Charles Lyell

Melania inquinata. Paris Basin.

Fig. 40.

Physa columnaris. Paris Basin.

Fig. 41.

Melanopsis buccinoidea; recent. Asia.

In regard to one of these, the Ancylus ([fig. 35.]), Mr. Gray observes that it sometimes differs in no respect from the marine Siphonaria, except in the animal. The shell, however, of the Ancylus is usually thinner.[29-A]