338 R. B. Newton — On Trematonotus. 



Bucania CMcagoensis ^ of an earlier date, and which is doubtless 

 synonomous with it, as pointed out by S. A. Miller.^ A second 

 species was recorded by Messrs. Hall and Whitfield,^ in 1875, as 

 T. (?) trig ono stoma, the authors placing a query against the genus 

 because they were unable to distinguish the perforations in con- 

 sequence of the obscurity of the dorsal region of their specimen. 

 Both these species were obtained from the Niagara formation of 

 Illinois and Ohio in the United States. 



Another Palaeozoic shell exhibiting a single row of openings on 

 its whorls is d'Orbigny's Pohjtremaria,* founded on De Koninck's 

 type oi' Pleurotomaria cateitata^ from the Carboniferous Limestone 

 of Belgium. This form is sufficiently distinct not to be confounded 

 with Trematonotus, being a small trochiform shell possessing a wavy 

 band round its volutions, resulting io a series of what may be 

 termed pseudo-perforations. De Koninck,^ following d'Orbigny,'' 

 relegated it to the Haliotidge. 



The genus Sniping ostoma ^ of F. Eoemer, is also a shell with 

 Bellerophontoid characters but having a wide umbilicus and bearing 

 on its dorsal region a single elongate slit considerably removed fi-om 

 the apertural margin. Its type is the Belleroplion megalastomn ^ of 

 Eichwald from the Silurian rocks of Russia. Dr. Paul Fischer 

 makes reference to another perforate shell under the name of Gyro- 

 trema,^^ but this is ascertained to be merely a manuscript genus of 

 Barrande's which has been used for list purposes by Dr. J. J. 

 Bigsby " and consequently of no zoological value until it is described 

 and figured. 



The Silurian genus Tuhina '^ from Bohemia has three rows of 

 tubular spines on its dorsal region, which, howevei', are rarely pre- 

 served, as they become detached and then have all the appearance of 

 true perforations. One specimen of this genus in the British Museum 

 exhibits the spines in situ and is the same species as that figured 

 in Sir Eichard Owen's " Palteontology " under the name of Taubin 

 armata, Barrande (MS.) This genus is placed by Dr. Fischer in the 

 Delphinulida3. 



The character of the orifices in Trematonotus was considered of suf- 

 ficient importance by Mr. Ralph Tate ^^ to claim the genus as a member 



^ Trans. Chicago Ac. Sci. 1859, vol. 1, pi. viii. figs. 4, 5, p. 69. 

 ' North American Geology and Palaeontology, 1889, p. 428. 

 3 Rep. Geol. Surv. Ohio, 1875, vol. 2, part 2, pi. 8, fig. 5, p. 146. 

 * Prodrome Paleontologie, 1849, vol. 1, p. 122. 

 = Dese. Anim. Foss. Carb. Belgique, 1844, pi. xxxii. fig. 1, p. 374. 

 6 Faun. Calc. Carbonif. Belgique, Ann. IVJus. E,. Hist. Nat. Belgique, 1883, 

 vol. 8, part 4, p. 10. 



' Cours elem. Paleontologie, 1852, vol. 2, p. 21. 



8 Lethcea geognostica (Palmozoica) 1876, pi. v. fig. 12. 



9 Silurische Schicht. Esthland, 1840, p. 111. 



10 Manuel Conchyl. 1885, p. 854. ii Thesaurus Siluricus, 1868, p. 167- 

 '- A manuscript name of Barrande's. Genus first figured and described by 



S. P. Woodward, in Sir Eichard Owen's "Palaeontology." 1860, pp. 71 (fig. 17, 

 No. 8), 78; a fuller description afterwards appearing by Dr. I'aul Fischer in his 

 "Manuel Conchyliologie," 1885, woodcut, fig. 587; pp. 8:<0, 831. 

 1^ Appendix, S. P. Woodward's Manual of MoUusca, 1868, p. 39. 



