182 
PALEONTOLOGY OF NEW YORK. 
Observations. No more decisive evidence of the close generic relations of 
Orthis and Rhynchonella than is furnished by this species, can be desired or 
expected. The shell is, in effect, a Platystrophia with shortened hinge, nar¬ 
rowed and acuminate beak, and well-developed crural processes; or the propo¬ 
sition is convertible; it is a Rhynchonella, with cardinal areas and uncovered 
delthyria on both valves. There is a singular anachronism in the sole appear¬ 
ance of this type of structure at a period so long after the distinctive ingredient 
stocks were well established, a fact which may, to some degree at least, be 
ascribed to our incomplete knowledge; at the same time there is an eminent 
fitness in the concurrence of this PLATYSTROPHiA-like Rhynchonella in a fauna 
with Platystrophia itself, at its highest and most varied development. 
Orthorhynchula Linneyi is rather widely distributed in the Hudson River fauna 
of Kentucky, but is not known to the eastward. 
Genus R H Y N C H 0 T RE M A, Hall. 1860. 
PLATE LVI. 
1842. Ab'ypa, Conkad. Journal Acad. Nat. Sci. Philadelphia, vol. viii, p. 264. 
1847. Atrypa, Hall. Paleontology of N. Y., vol. i, pp. 146-148, 289, pi. xxxiii, figs. ISa-y, 14 a-c; 
pi. Ixxix, fig. 6. 
1859. Rhynchonella, Hall. Twelfth Ann. Kept. N. Y. State Cab. Nat. Hist., pp. 65, 66. 
1860. Rhynchotrema, Hall. Thirteenth Ann. Kept. N. Y. State Cab. Nat. Hist., pp. 66-68, figs. 8-13. 
1873. Rhynchonella, Meek. Paleontology of Ohio, vol. i, j). 123, pi. xi, figs. 6 a-f. 
1875. Trematospira, Miller. Cincinnati Quarterly Journal of Science, vol. ii, p. 60. 
1889. Rhynchonella, Nettblroth. Kentucky Fossil Shells, p. 83, pi. xxxiv, figs. 26-29. 
This name, introduced more than thirty years ago, was designed to indicate 
a peculiar variation in structure, which is not often retained even in the type- 
species itself, though its absence is unquestionably due to accidental causes. On 
this account, perhaps, the term Rhynchotrema has failed of general adoption, 
and it is only quite recently that some writers* have indicated a disposition to 
employ it. 
* See Waagen, Salt-Range Fossils, p. 410. Dr. Waagen, taking as of prime importance the absence of 
dental lainellie in the typical species, has suggested the occurrence of the gi’oup among the Amei'ican De¬ 
vonian Rhynchonellas. Probably, however, the type of structure, of which the lack of dental lamellae is 
but a single element, was more narrowly restricted in its vertical range. CEhlbrt, in Fischer’s Manuel de 
Conchyliologie (1887), has also used the term, and accompanies it with some original figures, used in a pre¬ 
vious publication (Bull. Soc. G6ol. de France, 3® Ser., t. xii, p. 426, pi. 10, a, b), but which fail to show the 
critical characters of the genus. 
