WILLIAMS AN 
KINDLE, 
D j CONTRIBUTIONS TO DEVONIAN PALEONTOLOGY. 57 
LIST OF DIAGNOSTIC CHEMUNG SPECIES. 
By H. S. Williams. 
In the list below are given the species appearing in this southern 
extension of the fauna, which in New York are diagnostic of the Che- 
mung formation and immediately follow the Nunda (Portage) for- 
mation : a 
List of Chemung species. 
9. Delthyris mesicostalis. 
10. Sphenotus contractus. 
11. Edmondia, several species. 
12. Macrodon chemimgensis. 
13. Leptodesma lichas, and several other 
species. 
14. Mytilarca chemungensis. 
15. Pterinea (Vertumnia) reversa. 
1. Stropheodonta (Douvillina) mucrona- 
ta.» 
2. Strophonella cselata. 
3. Productella hirsuta. 
4. P. lachrymosa. 
5. P. stigmata. 
6. Dalmanella tioga. 
7. Atrypa hystrix. 
8. Spirifer disjunctus. 
The significant feature of the list is the absence of Stropheodonta 
{Leptostrophia) interstrialis Vanuxem, which is represented in the 
Ithaca faunas of New York; of Spirifer pennatus var. posterus, also 
an Ithaca species, and of the Productella which has generally been 
recorded as P. speciosaf and was described from the Chemung of 
western New York. This form is, however, frequent in the Ithaca 
formation, and the characters which have served to distinguish it from 
the form coming later in the Chemung, i. e., P. lachrymosa, are as 
follows: d 
Umbo [is] much elevated above the hinge line, with the apex closely incurved, 
regularly arcuate from beak to base, and more rapidly curving to the sides; abruptly 
depressed on the sides of the umbo, and concave between it and the narrow, short 
ears. c * * * The species resembles some of the forms of P. lachrymosa, but the 
spiniferous tubercles are smaller, more closely arranged, and more numerous, while 
the umbo of the ventral valve is narrower and somewhat abruptly alternate. e 
Figures 2, 4, 5, and 8 of PI. XXV of the report above cited well 
express these features. The forms of the Chemung which have like 
surface markings are found to resemble more closely the figured speci-* 
mens of P. hirsuta. Great variation is expressed in even a small col- 
lection of specimens from either horizon, and, while it is impossible to 
distinguish absolutely the earlier from the later forms, the characters 
above referred to are found in practice to be of considerable diagnos- 
tic value. 
The range of Dalmanella tioga (" Schizophoria tioga") is given in 
Mr. Schuchert's list as " Portage and Chemung" (Dev.)."' After con- 
siderable study of the range values of the Devonian species, the writer 
a See footnote, p. 86. dlbid., page 175. 
*>3ee note, p. 35. e ibid., page 176. 
o See Pal. N. Y.. IV, 1867, p. 175, pi. 25, figs. 1-11. / Bull. U. S. Geol. Survey No. 87, p. 375. See p. 36. 
