BRACHIOPODA. 
257 
Phillips* which form Mr. Davidson has regardedf as but a variety of Phillips’ 
Spirifer crenistria. 
This well known and widely distributed species (according to current au¬ 
thority), Spirifer crenistria, Phillips (= Streptorhynchus crenistria ), may hence be 
taken as the type of Orthothetes ; and since this fossil, as recognized, is sub¬ 
ject to considerable variation in the regularity and elevation of the umbo of the 
pedicle-valve, which is usually normal and symmetrical, but sometimes much 
distorted, it opens the genus to the reception of species in which this irregular¬ 
ity is usually present, and to those in which this condition does not appear. 
Genus HIPPARION YX, Yanuxem. 1842. 
PLATE IX, PIGS. 33-36; and PLATE XVa, PIGS. 9-11. 
1838. Leptasna unguiformis, Conrad. First Ann. Rept. Palaeont. Dept. N. Y. State Geol. Survey, 
p. 112 (not described). 
1840. Strophomena unguifoimis, Conrad. Third Ann. Rept. Palaeont. Dept. N. Y. State Geol. Survey, 
p. 203 (not described). 
1841. Atrypa unguiformis, Conrad. Fifth Ann. Rept. Palaeont. Dept. N. Y. State Geol. Survey, 
p. 36 (not described). 
1842. Hipparionyx proximus,^ anuxem. Geology of-N. Y.; Rept. Third Dist., p. 124, fig. 29, No. 4 
(not H. consimilis nor H. similaris , Vanuxem, p. 124). 
1843. Atrypa longuiformis, (Conrad) Hall. Geology of N.Y.; Rept. Fourth Dist., p. 149, fig. 60, No. 4. 
1859. Orthis hipparionyx, Hall. Palaeontology of N. Y„ vol. iii, p. 407, pi. lxxxix, figs. 1-4; pi. xc, 
figs. 1-7 ; pi. xci, figs. 4, 5; pi. xciv, fig. 4. 
1860. Orthis unguiformis, Emmons. Manual of Geology, p. 129, fig. 115. 
■1881. Orthis unguiformis, Davidson. ? Brachiopoda Budleigh-Salterton Pebble-bed, p. 347, pi. xxix, fig. 1. 
1883. Streptorhynchus hipparionyx, Hall. Second Ann. Rept. N.Y. State Geologist, pi. 39, figs. 33-36. 
Not Orthis hipparionyx, Schnur. 1853. Palaeontographica, vol. iii, p. 217, pi. xl, fig. 1. 
Not Orthis tiipparionyx?, Davidson. 1S65. British Devonian Brachiopoda, p. 90, pi. xvii, figs. 8-11. 
The remarkable shell described by Dr. Yanuxem as Hipparionyx proximus, so 
far as known, is the only representative of a peculiar association of streptor- 
hynchoid characters. The name Hipparionyx has not been in general use, 
though, in the broad application of the generic term, which has been customary 
in this group of shells, it should have had precedence over Streptorhynchus. 
Schnur, in 1853, regarding what he believed to be a similar shell from the 
Eifel as an Orthis, took the liberty of changing Vanuxem’s name for the species 
* Geology of Yorkshire, vol. ii, p. 220, pi. xi, tig. 4. 1836. 
f British Carboniferous Brachiopoda, p. 127 ; British Devonian Brachiopoda, p. 81. 
