186 HISTORICAL PALAAONTOLOGY. 
and South America; whilst P. Jongispina (fig. 127, 6) has a 
distribution little if at all less wide. 
The higher J/olusca are abundantly represented in the 
Carboniferous rocks by Bivalves (Lamedlibranchs), Univalves 
(Gasteropoda), Winged-snails (Pteropoda), and Cephalopods. 
Amongst the Bivalves we may note the great abundance of 
Scallops (Aviculofecten and other allied forms), together with 
numerous other types—some of ancient origin, others repre- 
sented here for the first time. Amongst the Gasteropods, we 
find the characteristically Paleozoic genera Macrocheilus and 
Loxonema, the almost exclusively Paleozoic ELuomphalus, and 
the persistent genus Pleurotomaria ; whilst the free-swimming 
Univalves (/e¢eropoda) are represented by Bellerophon and Porcel- 
Zia, and the Preropfoda by the,old genus Conularia. With regard 
to the Carboniferous Univalves, it is also of interest to note here 
the first appearance of true air-breathing or terrestrial Molluscs, 
as discovered by Dawson and Bradley in the Coal-measures of 
Nova Scotia and Illinois. Some of these (Conulus priscus) are 
true Land-snails, resembling the existing Zonzfes ; whilst others 
(Pupa vetusta, fig. 128) appear to be generically inseparable 
from the ‘ Chrysalis-shells ” 
(Pupa) of the present day. 
All the known forms—three 
in number—are of small size, 
and appear to have been local 
in their distribution or in their 
preservation. More import- 
ant, however, than any of the 
preceding, are the Cephalh- 
poda, represented, as_ before, 
exclusively by the chambered 
shells of the Tetrabranchiates. 
The older and simpler type of 
these, with simple plain septa, 
and mostly a central siphuncle, 
is represented by the straight 
conical shells of the ancient 
Fig. 128.—Pupa (Dendropupa)vetusta, genus Orthoceras, and the bow- 
2 Carboniferous Landanall from the Coal shaped shells of the equally 
the natural size; 4, The same, magnified ; ancient Cyrtoceras == some Gt. 
c, Apex of the shell, enlarged; ¢@, Portion Saas ¥ ee 
of the surface, enlarged. (After Dawson.) the former attaining a gl eat s1ze. 
; The spirally-curved discoidal 
shells of the persistent genus /Vawfi/us are also not unknown, 
and some of these likewise exhibit very considerable dimen- 
sions. Lastly, the more complex family of the dAmmonitide, 
