44 PAL/EONTOLOGY OF NEW YORK. 



but probably serving as a taunal equivalent of the Niagara and Guelph forma- 

 tions. No species are known in Great Britain, those from the Island of Got- 

 land, and from Livonia, Russia, are from faunas cori'esponding to that of the 

 Niagara and Wonlock. 



■"B^' 



Genus RHINOBOL US, Hall. 1871. 



PLATE IV II, FIGS. 7-12. 



[1] 1862. Obiilus, BiLLi.vfiS. Piilaiozoic Fossils?, voL i, p. 1138, lig-. 1:')!. 



1871. Triiaerella. Dai.i,. American Journal of Concliology, voL vii, p. 83. 



1871. Rhynohohis, H.vll. Advance sheets (March) Twenty-thii'd Rept. N. Y. State Cal>. Nat. Hist., p. 



247, pL xii, fig-. 10. 1S7S. 

 [?] 1871. Oboldlina, Billings. Canadian Naturalist, vol. vi. New Series, p. 220 (December). 



1872. DinoboliiS, Davidson and King. Report Brighton Meeting of British Association. 



1874. lYimcrella (.'), Davidson and King. Quart. Journ. Geological Society, voL xxx, p. ITil, pi. xviii, 



fig. 13 ; pi. xix, figs. 4, 4a. 

 [1] 1884. Hhynobolus, Whitbaves. Paheozoic Fossils, voL iii, pt. 1, p. 7, jil. ii, fig. la; pi. viii, figs. 3, 3a. 



Diagnosis. General form of the shell as in Trimerella. 



Pedicle-valve, iu the typical species, with an elevated, solid beak, having a 

 broad and high deltidium, divided into a relatively narrow central area (which 

 may be concave or convex), and broad deltidial ridges. Crescent and terminal 

 scars as in Trimerella. Umbo-lateral scars sharply defined. Platform very low 

 and incompletely developed, consisting of a broadly V-shaped elevation, with 

 a raised anterior margin, and surface sloping abruptly backward to, or even 

 below the general curvature of the internal surface. A faint longitudinal sep- 

 tum extends forward from the platforui. 



Brachial valve witli low, suli-niarginal, slightly curved apex, and short delti- 

 dium. Crescent conspicuously developed. Platform as in the opposite valve, 

 with the addition of a central scar, which gives the entire area a tripartite 

 appearance. Median septum faint. 



Type, ''Rhynobolus- .? " Hall. (1871, loc. ciL, pi. xii, fig. 10.) 



Orservations. The description of the genus Rhinobolus (erroneously printed 

 Rhynorolus) Avas based upon the interior of a pedicle-valve, characterized as in 

 the foregoing diagnosis. At the time of the publication of the generic term, 

 this valvi' had not been positively identified with the Obolus Galtensis of BiWings 



