WAVEELY GEOUP SPECIES 287 



ville, Kentucky, as with S. Carteri, originally described from the Waverly 

 group of Ohio. Its area is proportionally somewhat larger, flatter, and 

 less arched, as well as more distinctly defined, than it appears to have 

 been in the typical specimens of S. Carteri; but the margins of its area 

 are still less sharply defined, and the lateral slopes of its ventral valve 

 less flattened, and less abruptly inclined forward, than in the type for 

 which the name S. textus was proposed. These, however, are usually such 

 variable characters in shells of this kind that we may generally ques- 

 tion the propriety of viewing them as specific differences, unless accom- 

 panied by some more constant and reliable distinguishing features. 



The shell for which Prof. Swallow proposed the name Spirifer {Cyrtia?) 

 Hannibalensis seems to agree in its specific characters with the Ohio 

 form under consideration ; and I even suspect that Spirifer capax, Hall, 

 and Syringothyris typvs and S. Halli, of Winchell, may possibly be varie- 

 ties of the same species. It is true I have not seen specimens of the 

 Ohio shell in a condition to show whether or not it possess the punctate 

 structure seen in Prof. Winchell's types, as well as in most of the others 

 already mentioned, but it certainly has the same deep-seated septum and 

 internal tube as Syringothyris (see markings in cast at -|- of fig. 7c); and 

 from this fact, and all of its other characters, it may be regarded as 

 almost morally certain that it has the same shell structure. 



Again, it will be observed that all of these shells bear very close rela- 

 tions to the various forms or varieties referred by the highest European 

 authorities to the common and widely distributed Spirifer cuspidatus, 

 Martin. None of the specimens of the Ohio shell under consideration 

 that I have seen have the area and beak of the ventral valve so extrava- 

 gantly, elevated as some of those of S. cuspidatus figured by Mr. David- 

 eon and others ; but this is a variable character, some of the figures of 

 the European shell not differing materially from ours in this respect.* I 

 have not seen any examples of internal casts of iS. cuspidatus; but if the 

 specimen represented by our figure Id really belongs to the species under 

 consideration (of which there may be some doubts), it would seem not 

 to agree very well with Mr. Davidson's description of the interior of the 

 corresponding valve of S. cuspidatus. 



The only characters mentioned, by Prof. Hall as distinguishing his S. 

 textus from S. cuspidatus were the supposed greater number of costaB, and 

 the peculiar minutely pitted or textile appearance of the surface in the 

 former. But he described both his S. textus and S. Carteri as having only 

 from eighteen or nineteen to twenty costse or plications on each side of 

 the mesial fold and sinus, while Mr. Davidson gives thirty to forty-four 



* Mr. Davidson mentions that there are all gradations from specimens with, a com- 

 paratively low area to the typical forms of S. cuspidatus. 



