GEOLOGY OF THE FOURTH DISTRICT. 
ORGANIC REMAINS OF THE NIAGARA GROUP. 
No. 12. — No. 35, page 104 of Report. 
Fig. 1. Strophojnena subplana, C. (Jour. Acad. Nat. Sci., vol 8, page 258.) Lockport. 
Fig. 2. Strophomena depressa, Productus depressus, M. C. t. 459. ( Leptcena depressa, Dal- 
man. Swedish Transactions, p. 106, t. 1, f. 2 ; Hisinger, Petrefacta Suecica, 
p. 69, t. 20, f. 3. Murchison, Silurian Researches, p. 623, pi. 12, f. 2.) An 
abundant fossil in the shale of the Niagara group. Lockport. 
Fig. 3. Strophomena striata , H. Common at Rochester and Lockport. 
Fig. 4. Strophomena transversalis. ( Leptcena transversalis, Dalm. 1. c. p. 109, t. 1, f. 4; 
His. Pet. Suec. p. 69, t. 20, f. 5. Silurian Researches, p. 629, pi. 13, f. 2.) 
No. 13. — No. 36, page 105 of Report. 
Fig. 1. Delthyris Niagarensis, Conrad (Jour. Acad. Nat. Sci. vol. 8, p. 261). Lockport. 
Fig. 2 and 2 b. Delthyris radiatus. (Spirifer radiatus, M. C. t. 493. Silurian Researches, p. 
624, pi. 13, f. 6.) Lockport. 
Fig. 3 and 3 b. Delthyris staminea , PI. (References, Spirifer crispus ? Silurian Researches, 
p. 624, pi. 13, f. 8. Delthyris crispa, Dalm. 1. c. p. 122, t. 3, f. 6; His. Pet. 
Suec. p. 73, t. 21, f. 5). Lockport. 
Fig. 4 and 4 a. Delthyris decemplicata, H. Lockport; and Delthyris sinuatus. ( Terebratula 
sinuata, Sowerby in Linn. Trans. Vol. 12, p. 516, t. 28, f. 5 and 6. Delthyris 
cardiospermiformis, His. Anteckn. Vol. 4, t. 7, f. 6. Dalm. sur les Terebratules, 
p. 124, t. 3, f. 7. His. Pet. Suec. p. 74, t. 21, f. 9. Spirifer cardiospermiformis , 
Von Buch sur les Spirifers et Orthis, t. 1, f. 7. Spirifer sinuatus, Silurian 
Researches, p. 630, pi. 13, f. 10.) Wolcott. 
Fig. 5. Orthisflabellulum ( a)? (Silurian Researches, pi. 21, f. 8. O. callactis ? Dalman.) 
Lockport. 
Fig. 6. Orthis canalis, (Silurian Researches, p. 630, pi. 13, f. 12, a; also pi. 20, f. 8. Orthis 
elegantula ? Dalman. Von Buch sur les Spirifers et Orthis, pi ii, f. 3, 4 and 5.) 
Sweden, Monroe county. 
Fig. 7, a, b, c. Orthis hybrida. (Silurian Researches, pi. 13, f. 11.) Sweden, Monroe county. 
No. 14 — in part No. 37, page 108. 
Fig. 1. Atrypa imbricata. ( Terebratula imbricata, Silurian System, p. 624.) 
Figs. 2 and 3. Atrypa. (Species undetermined.) Lockport. 
Fig. 4 and 4 a. Atrypa cuneata. ( Terebratula cuneata, Dalman. Hisinger. Silurian Re¬ 
searches, p. 625, pi. 12, f. 13.) 
Fig. 5. Atrypa nitida, H. A very abundant species, but usually more or less distorted. 
Lockport. 
Fig. 6. Atrypa offals , (Terebratula affinis. M. C. t. 324, f. 2. A. reticularis, Dalman, 
Hisinger, &c.) 
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