No. 8.] J. W. DAWSON — PALEOZOIC LAND SNAILS. 455 



late Dr. Carpenter as probably a near ally of those species which 

 are placed by some European conchologists in the genus Pupilla. 



The lowest bed in which Pupa vetusta occurs belongs to 

 group VIII of Division 4 of my section of South Joggins, and 

 is between Coal 37 and Coal 38 of Logan's Section, being about 

 42 feet below Coal 37. The next horizon, and that in which the 

 shell was first discovered, is 1217 feet of vertical thickness 

 higher, in group XV of Division 4 of my section. The shells 

 occur here in erect SigiUarice, standing on Coal 1 5 of Logan's 

 section. The third horizon is in group XXVI of Division 4, 

 about 800 feet higher than the last. Here also the shells occurred 

 in an erect SigiUaria. 



In the lowest of these three horizons, the shells are found, as 

 already stated, in a thin bed of concretionary clay of dark gray 

 color, though associated with reddish beds. It contains Zonites 

 priscus as well, though this is very rare, and there are a few 

 valves of Cythere and shells of Naiadites, as well as carbonaceous 

 fragments, fronds of ferns, Trigonocarpa^ etc. The Pupce, are 

 mostly adult, but many very young shells also occur, as well as 

 fragments of broken shells. The bed is evidently a layer of mud 

 deposited in a pond or creek, or at the mouth of a small stream. 

 In modern swamps, multitudes of fresh water shells occur in such 

 places, and it is remarkable that in this case the only gastero- 

 pods are land shells, and these very plentiful, though only in one 

 bed about an inch in thickness. This would seem to imply an 

 absence of fresh-water Pulmonifera. In the erect SigiUarice of 

 Group XV, the shells occur either io a sandy matrix, more or 

 less darkened with vegetable matter, or in a carbonaceous mass 

 composed mainly of vegetable debris. Except when crushed or 

 flattened, the shells in these repositories are usually filled with 

 brow^nish calcite. From this I infer that most of them were alive 

 when imbedded, or at least that they contained the bodies of the 

 animals ; and it is not improbable that they sheltered themselves 

 in the hollow trees, as is the habit of many similar animals in 

 modern forests. Their residence in these trees as well as the 

 characters of their embryology are illustrated by the occurrence 

 of their mature ova. They may also have formed part of the 

 food of the reptilian animals whose remains occur with them. 

 In illustration of this, I have elsewhere stated that I have found 

 as many as eleven unbroken shells of Physa lieterosfropha in the 

 stomach of a modern Menohranclius. I think it certain, however, 



