GASTROPODA. 865 
Oyrtolites dilatatus.] 
grown specimen. Surface markings on the whole nearly the same as in C. ornatus, 
only the transverse ridges are not confined to the dorsal slopes but continue down- 
ward with a slight retral curve over the ventral slopes as well. The reticulation 
of the surface also changes with growth in a manner not observed in that species. 
Thus on the minute inner whorl the surface is almost smooth, only a few obscure 
revolving lines being visible on this part. With the beginning of the second turn 
the sculpture changes abruptly to the usual style of reticulation, but for some 
‘distance the transverse lines curve backward towards the dorsal carina as in C. 
retrorsus and C. carinatus. This retral curve, however, is soon lost so that on the 
greater part of the shell they pass directly over the carina as in C. ornatus. : 
The peculiarities of this beautiful shell are so obvious that comparisons are 
quite unnecessary. It is the only species of the genus in which the whorls are not 
in contact. 
Formation and locality.—Richmond group of the Cincinnati period, near Spring Valley, Minnesota, 
where two specimens were found in association with Orthis subquadrata and numerous other Brachiopoda 
characterizing the horizon. 
Collection.—K. O. Ulrich. 
CYRTOLITES (?) DILATATUS, ”. sp. 
PLATE LXII, FIGS. 20—26. 
Shell 15 to 30 mm. in hight, the inner volutions unknown, the outer expanding 
very rapidly in width, sharply carinated or alated on the sides, more obtusely upon 
the back, transversely triangular quadrate in section; dorsal slopes flat except near 
the prominent lateral edges where they are concave; ventral side nearly flat, with 
a central groove probably for the reception of the dorsal carina of the inner volu- 
tions; aperture nearly or about twice as wide as high, subtriangular, the width 
slightly exceeding the hight of the entire shell, the outer margin with a broad, 
centrally angular sinus, the inner lip with a small “saddle.” Surface markings 
unknown; outer part of a large cast of the interior with a few faint transverse 
wrinkles of growth. 
Of this remarkable species we have seen but two specimens, one, a large cast of 
the interior, belonging to the Powers’ collection of the University of Wisconsin, the 
other a smaller testiferous example collected by KE. 0. Ulrich in Minnesota. The 
latter exhibits no signs of surface markings, but this is evidently due to lack of 
preservation. In the absence of any knowledge of the superficial sculpture, the 
generic position is somewhat doubtful. The great width of the aperture and the 
wing-like expansion of the lateral edges are suspicious and possibly indicate a 
relation to Carinaropsis. When fully known we believe it will be recognized as 
—55 
