GASTROPODA. 929 
Carinaropsis minima.] 
CARINAROPSIS MINIMA, %#. Sp. 
PLATE LXII, FIG. 19. 
Shell very small for the genus, the width of the aperture about 8 mm. in a 
specimen having a length of 6 mm. and a concavity of about4.3 mm. Dorsum only 
moderately acute at first and becoming gradually quite obtuse. Surface with 
several comparatively strong lines or wrinkles of growth. 
Of this species we have seen only the small specimen figured on plate LXII. 
At first we thought it might be an immature example of C. phalera, but a more 
careful comparison proved conclusively that so great an expansion of the aperture 
could not have occurred in the young of that species. Indeed, the expansion of the 
aperture isa sign of maturity in this genus, and that this condition has been reached 
by the specimen in question is further indicated by the strength of the lines of 
- growth which mark its surface where the latter is in good preservation. If these 
indications are trustworthy then the species will be distinguished very readily from 
all the others known of the genus by its small size. 
Formation and locality.—Black River group (Ctenodonta bed) near Cannon Falls, Minnesota. 
Collection.—E. O. Ulrich. 
CARINAROPSIS EXPLANATA, 7. sp. (Ulrich.) 
PLATE LXIf, FIG. 5. 
Shell large, volutions apparently less than two, the first very small, the next 
greatly expanded; hight only about one-third of the width; umbilicus very small; 
dorsum angular. Aperture not well preserved, apparently transversely subelliptical, 
and somewhat broadly sinuate in front; posterior lip little if at all reflected. Septum 
large, curved inward, the inner edge about 18 mm. long in a specimen 38 mm. wide. 
Surface of casts with obscure varices of growth. 
The width is relatively greater than in any of the other species. The outer 
surface of the septum is less deeply concave and its anterior edge farther within the 
plane of the apertural margin than in C. cymbula, which it resembles perhaps more 
closely than the others. 
Formation and locality.—Upper part of the Trenton group, Covington, Kentucky. 
Collection.—E. O. Ulrich. 
—59 
