38 PALEONTOLOGY. 



RHYNCHONELLID^. 



? Genus ATRYPA, Dalman. 



Atrypa reticularis, LinuiEiis (sp.). 



Plate 1, figs. 7 iuui 7 a ; and Plate 3, figs. G ? and 6 a. 

 Anomites reticularis, Liunseus (17G7), Syst. Nat., XII, ed., 1152.— Wablenb. (1821), 



Nov. Act. Soc. Upsal., VIII, 65. 

 Terehratula peetinata, Brugui^re (1789), Hist. Nat. Vers. Test. Encyc. M6tli., 242, fig. 4. 

 Terebratulites 2)riscus, Schlot. (1820), Petref., ^G2 ; Nacbt., pL xvii, fig. 2, and pi. xx, 



fig. 4. 

 Terebratulites explanatus, Schlot. (1820), Naclit., pi. xviii,flg. 2. 

 Terehratula affmis, Sowerby (1822), Mia. Conch., IV, 324, fig. 2. 

 Atrypa reticiilaris, Daliuan (1827), Vet. Akad. Verhandl., 127, pi. iv, fig.* 



Of this widely-distributed form, there are numerous specimens in the 

 collection from several localities, presenting all the characters of the species, 

 with the limits usually assigned it. As it is too well known to require a 

 detailed description, I would merely remark that the specimens from Pinon 

 Station are larger and more robust than any of the others from the other 

 localities, and closely resemble, not only in form and surface-markings, but in 

 their .state of preservation (being silicified), the numerous examples found 

 in the Upper Helderberg limestones near Louisville, Kentucky. They were 

 also found associated with a Spirifer, very closely allied to one of the Louis- 

 ville species of that horizon. 



The other specimens, from the silver-bearing, dark- colored limestone at 

 Treasure Hill, White Pine District, and other localities, are all of smaller 

 size, and not silicified. Some of these are finely striated, as represented by 

 our fig. 6 a of plate 3, while others have the surface more coarsely striated 

 or costated, as represented by fig. 6 of the same plate, and thus more nearly 

 approach A. aspera, Schlotheim (sp.), to which possibly they might with 

 more propriety be referred.f As there are, however, among the specimens 

 • For the long list of additional synonyms of this species, as most generally 

 nnderatood, see Mr. Davidson's Monograph British Silurian Brachiopoda, 130. 



+ Some reliable authorities believe that, even alter separating A. aspera and some 

 other forms often included as varieties, this name is made to include several dis- 

 tinct species. Never having made an especial study of the group, however, I have 

 here iiiclnded provisionally a few forms that a strict classification might possibly 

 require should be separated under some of the published names. 



