44 
PALAEONTOLOGY OF NEW YORK. 
but probably serving as a faunal 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 corresponding to that of the 
Niagara and Wenlock. 
Genus RHINOBOLUS, Hall. 1871. 
PLATE IV B, FIGS. 7-12. 
[?] 1862. Obnlus, Billings. Palaeozoic Fossils, vol. i, p. 168, fig-. 151. 
1871. Trimerella, Dall. American Journal of Conchology, vol. vii, p. 83. 
1871. Rhynobolus, Hall. Advance sheets (March) Twenty-third Rept. N. Y. State Cab. Nat. Hist., p. 
247, pi. xii, fig. 10. 1873. 
[?] 1871. Obolellina, Billings. Canadian Naturalist, vol. vi, New Series, p. 220 (December). 
1872. Dinobolus, Davidson and King. Report Brighton Meeting of British Association. 
1874. Trimerella (?), Davidson and King. Quart. Journ. Geological Society, vol. xxx, p. 151, pi. xviii, 
fig. 13; pi. xix, figs. 4, 4 a. 
[1] 1884. Rhynobolus, Whiteaves. Palaeozoic Fossils, vol. iii, pt. 1, p. 7, pi. ii, fig. la; pi. viii, figs. 3, 3a. 
Diagnosis. General form of the shell as in Trimerella. 
Pedicle-valve, in 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 platform. 
Brachial valve with low, sub-marginal, 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. cit., pi. xii, fig. 10.) 
Observations. The description of the genus Rhinobolus (erroneously printed. 
Rhynobolus) was 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 valve had not been positively identified with the Obolus Galtensis of Billings 
