376 UNITED STATES GEOLOGICAL SURVEY OF THE TERRITORIES. 



tinct to require a different name, either as a species or as a variety, it may 

 be called Fususl (Serrifusus) goniophorus. 



1 should explain, however, that these forms are much more nearly 

 related than would be supposed from a comparison of our figured specimens ; 

 that of the larger typical F. Dakotensis having its upper volutions broken 

 and eroded, so as to round off the angles and nodes, thus giving it a different 

 aspect from some broken, smaller examples of the same in the collection. 

 Still, none of the latter yet seen have the upper slope of the volutions so con- 

 cave, the carina? near so sharp, or the nodes of the same so compressed and 

 transverse: while, like the large one figured, they have the spire more 

 depressed than the form here under consideration, and the revolving lines 

 much more distinct on the lower part of the body-volution. 



The artist did not succeed in representing the carinas exactly right on 

 the body-volution of this form in figure 7, a, as he drew a mere raised hair- 

 line between the two principal ridges, much too strong, thus giving the 

 appearance of three of those of the smaller size, while there are only two. 

 The angle on the upper volutions is also made to appear too much like a con- 

 tinuous keel, instead of being scalloped into little transverse serrations. 

 Since the plate was engraved, I have also found, by cutting away the rock 

 about the columella, that it is more arcuate opposite the middle of the aper- 

 ture, and more prominent on the inner side, just above where the canal is 

 broken off than appears in the figure. 



I am in some doubt whether the little specimen represented by our 

 figure 7, b, belongs properly to the variety or species here under consider- 

 ation, or to the last. In the concavity of the upper slope of its volutions, and 

 the nature of its carina 1 , it agrees more nearly with the shell here under con- 

 sideration ; but, in general form, it is more like the last. Here, too, the 

 carina? arc, however, not exactly right in the figure ; the mere hair-line 

 first below the upper ridge, being drawn too large; while there is another 

 revolving line, or ridge, represented below all, that does not exist on the 

 specimen. 



As already intimated, this shell resembles, in many respects, an East 

 Indian Cretaceous species described by Dr. Stoliczka under the name Lagena 

 nodulosa more nearly than any other form with which I am acquainted; 

 though our shell has a more produced spire, a proportionally less ventricose 

 body-volution, and wants a kind of tootli or projection on the inner lip, seen 



