1889 ] 
275 
[Foerste. 
sharply down to the next annotation. A cast of the outer surface 
shows a much more even surface broken by annulation of a less 
marked character, the depressions separating them being broad and 
shallow instead of sharp and abrupt as in the cast. 
Cornulites Clintoni also occurs in the collections from Collins- 
ville, Alabama. 
The exterior of the New York specimens shows usually but a 
moderate amount of vesicular tissue in the walls of the tube defin- 
ing the interior annulations. Usually the interior casts if well 
preserved show one — perhaps more — longitudinal striae, sunk in 
a narrow groove. The exterior has the same number of annula- 
tions as the interior cast. These exterior annulations are never 
as sharply defined on the aboral side, as are the interior casts, but 
still they are usually more distinct on that side. 
This species differs from Cornulites proprius, Hall, from the Niag- 
ara of Indiana, in having far more regular annulations, and the ex- 
terior annulations corresponding much more closely with those of 
the interior casts. There are also less transverse striations, and 
those that do exist are not so coarse. Longitudinal striations 
are also less evident. The young of Cornulites proprius are also 
curved. 
Both Cornulites serpularius , Schlotheim, as identified by Sowerby , 
and Cornulites Clintoni as described by Hall, contain two forms, 
one in which the annulated casts are straight or nearly so and their 
rate of increase is quite regular, and another in which these casts 
are more or less bent and in which the rate of increase is quite 
irregular. These shells are apt to be more bent towards the 
smaller extremity. In the New York Clinton the bent forms are 
quite rare, at least as far as I have learned. In the Clinton of the 
southern states we have found only straight forms. 
It is difficult to identify the young of Cornulites Clintoni in New 
York. While I have not been successful I have at least a few sug- 
gestions to make. It is probable that the young of the adult curved 
forms of Cornulites serpularius of Europe are curved. May it not 
be the case that on account of the comparative scarcity of the adult 
curved form in New York the small curved young have escaped de- 
tection ? On the other hand, there seem to be straight young speci- 
mens both in this country and in Europe which might prove to be 
the young of those which are straight when adult. In the collec- 
tions from New York, Cornulites distans is such a small, straight 
