388 TWENTIETH REPORT ON THE STATE CABINET. 



the species he referred to P. halei, the specimens which he sent to me 

 under the latter name are not of that species, but of Pleurotoiyiaria 

 {Trochonema ?) pauper. In Prof. Marcy's collection there are numerous 

 specimens of the latter species, and one fine cast of P. halei; but neither 

 in this collection, nor in that sent by Prof. Winchell, is there any speci- 

 men of P. axion. 



On page 98 of the Memoir, Prof. W. has added to Hall's description 

 of P. halei certain other characters, which are not known to belong to thnt 

 species, and it would have been as well, perhaps, to have been sure of the 

 identification, before extending or correcting the description. The cast of 

 the umbilical cavity supposed to belong to this species, referred to on page 

 98, and communicated under that name by Prof. W., is the cast of the 

 umbilical cavity of the left side of Tremanotus alpheus, and presents a 

 sinistral aspect and peculiarly striated surface not belonging to the umbi- 

 licus of any species of Pleurotomaria or other similar turbinate shell. 



" (e). Tremanotus, Hall, is a new subgenus of Porcellia, founded 

 "upon our Belleropho/i (Bucania) pei'foratus. We may have sufficient evi- 

 " dence of the existence of dorsal perforations in this species. Neverthe- 

 " less the perfectly symmetrical enrolment of even the young shell, as 

 " well as the enormously expanded aperture (not seen by Hall), would 

 "seem to indicate stronger affinities with Bellerophon than with 

 " Porcellia." 



Since my publication was made a year or more in advance of that here 

 cited, it seems to me that the language '■''founded upon our Bellerophon 

 perforatus''' scarcely conveys the correct impression ; and still it must have 

 been so intended, since Prof. W. says at the outset (5, p. 108), that these 

 '•''have been identified hy us with established forms •,''^ ergo, Bellerophon 

 perforatus [nodarius^ ms.) is an established form.* As a subgenus of Por- 

 cellia, I see no objection to ''''the symmetrical enrohnent of even the 

 young shell C^ and had the spire been oblique, except at the apex which 

 I have not seen, I should scarcely have referred it to Porcellia; nor 

 do I intend to deny its affinities with Bellerophon by any means, 

 since it seems to me to constitute a genus intermediate to the two Genera 

 Porcellia and Bellerophon, or to Porcellia and Bucania. I 

 have not been ignorant of the expanded aperture, having thus described it.t 



*This is not the first time I have had occasion to remark a similar mode of reasoning in 

 the writings of Prof. Winchell. In a paper published some years since in the proceed- 

 ings of the Phil. Acad. Nat. Sciences; in the course of some remarks on the Genus 

 (iNGOTHYRis, Prof. W. says "There are reasons for believing that Spirifer extenuatus, 

 " Hall, from the yellow sandstones at Burlington, will yet be found to possess the same 

 *' peculiarities, if it is not a variety of one of the following species,'' which he proceeds 

 to describe. And so it may yet be found that species described by me many years since, will 

 prove varieties of species about to be described or of others yet to be described. It will be 

 a consolation, however, to learn which are the species and which the varieties : since it 

 would appear that in describing a species with from ten to one hundred individuals 

 before him, " the author might not have had the true type in the collection under investiga- 

 tion;" but it may subsequently be discovered in a single specimen by another person. 



I The first specimen of this species I ever saw, was in a collection brought from Illinois 

 by Prof. C. U. Shepard, and placed in the Collection of the Lowell Institute in 1840 or 1841. 

 The expanded and deeply striated aperture induced me, at that time, to regard the specimen 

 as identical with Bellerophon dilatatus, Sowebby (Murchison's Silurian System: Siluria, 

 plate 25, figs. 5 and 6). 



