GASTROPODA. 1021 
Solenospira.] 
Genus SOLENOSPIRA, n. gen. 
EHunema (part.) of SALTER and BILLINGS. 
Murchisonia (part.) of WHITFIELD and other authors. - 
For generic characters see page 959. 
This is a long-lived group of species that can always be recognized by the broad 
saliently margined concave band which occupies the greater part of the middle 
third of the whorls. In their general appearance they remind one of Turritellide 
rather than pleurotomaroids, and so far as we can see there is no serious objection 
to considering them as the ancestors of that graceful family of shells. 
So far as known the notch or sinus in the outer lip was never prolonged into 
a slit. This of itself is a suspicious circumstance when we consider the usual 
progress of development pertaining to nearly all of the various types of the 
Pleurotomariide. The proportionally great width of the band, together with the 
fact that its transverse markings are of the same character as the fine recurved 
lines of growth—indeed they are mere connecting continuations of them—strength- 
ens this suspicion almost to conviction that Solenospira represents the root of a line 
of development that later on (in Carboniferous and subsequent times) diverged 
widely from ordinary pleurotomarians. And what family is a more likely continu- 
ation of the line than the Turritellide? 
We place the genus with the Pleuwrotomariide, in the immediate vicinity of 
Hormotoma, chiefly because we know of no other stock from which it might have 
been derived. The depth of the apertural sinus and the fact that its deepest part is 
marked off in such a manner that with continued growth of the shell it formed a 
sharply margined spiral band, are both highly characteristic conditions of the 
Pleurotomariide, while the features mentioned in the preceding paragraph are such 
only as might very well have occurred in the separation of a line culminating in 
Turritella. 
The oldest of the species which we place here is the Eunema prisca Billings of 
the Calciferous formation of Canada. An apparently undistinguishable form, 
occurring in the Stones River group in Minnesota, Wisconsin, Illinois and Tennessee, 
is described and figured in this work. The Quebec group furnishes two other 
speciss, Murchisonia adelina and M. missisquoi of Billings. The latter of these two 
species possibly may, when better known, prove to have other affinities. In the 
Black River group we have the type of the genus, Hunema ? pagoda Salter. We 
know of no other good representatives of the genus, in American deposits, at 
any rate, until we reach the Hamilton group, from which Hall has described one as 
Murchisonia turricula, or as itis now known, M. micula, the specific name having 
