508 



LAMELLIBRANCHIA TA. 



[PTE. 



tusely pointed anterior end, from which 

 the ventral margin extends to the 

 broad posterior end ; left valve most 

 convex; internally a very small tooth 

 under the beak of the right valve, and 

 a very slender, posterior, lateral tooth 

 close to the hinge-line the whole length. 

 Type P. angustatus. 



gayensis, Dawson, 1868, Acad. Geo., p. 

 301, Subcarboniferous. 



gayensis var. ornatus, Dawson, 18S3, Rep. 

 on Redpath Mus., No. 2, p. 14, Subcar- 

 boniferous. 



inoptatus, Hall, 1884, Pal. N. Y., vol. 5, 

 pt. 1, p. 239, Chemung Gr. 



newarkensis, Meek, 1871, Proc. Acad. Nat. 

 Sci., p. 162, Waverly Gr. 



nanum, Hall, 1885, Pal. N. Y., vol. 5, p. 

 353, Chemung Gr. 



Fig. 907.— Pterouites profundus. 



profundus, Hall, 1884, Pal. N. Y., vol. 5, 



pt. 1, p. 237, Up. Chemung Gr. 

 rostratus, Hall, 1884, Pal. N. Y., vol. 5, pt. 



1, p. 238, Chemung (lr. 

 spergenensis, Whitfield, 1882, Bull. Am. 

 Mus. Nat. Hist., No. 3, p. 56, War- 

 saw Gr. 



Ptychodesma, 

 Hall & 

 Whitfield, 

 1872, 24th 

 Rep. N. Y. 

 Mus. Nat. 

 Hist., p. 

 192. [Ety. 

 ptychos, a 

 folding ; 

 desma, a 

 1 igament, 

 or band.] Form modioloid ; hinge hav- 

 ing a wide ligamental area, grooved by 

 the successive growth of the ligament, 

 as in pectunculus. Type P. knappa- 

 num. 



Fig. 908.— Ptychodesma knap- 

 panum. Right side. 



FlG. 909.— Ptychodesma knappanum. Enlarge- 

 ment of one side of ligamental area. 



knappanum, Hall & Whitfield, 1872, 24th 

 Rep. N. Y. Mus. Nat. Hist., p. 192, Up. 

 Held. Gr. 



minor, Hall, 1885, Pal. N. Y., vol. 5, p. 

 353, Chemung Gr. 



Fig. 911.— Ptychopteria 

 beecheri. 



Fig. 910.— Ptychopteria beecheri. 



Ptychopteria, Hall, 1884, Pal. N. Y., vol. 



5, pt. 1, p. 3. [Ety. ptyche, fold ; Pteria, 



a genus.] Differs from Actinopteria in 



the nasute anterior extremity, and 



large, straight wing marked by a 



strong longitudinal fold. Hinge-line 



narrow, linear; furnished with one 



or two linear, oblique, cardinal and 



lateral teeth ; surface with fine rays. 



It bears about the same relation to 



Actinopteria that Leptodesma does 



to Liopteria. Type P. eugenia. 



alata, Hall, 1884, Pal. N. Y., vol. 5, pt. 



1, p. 139, Chemung Gr. 



beecheri , 



Hall, 1884, 



Pal. N.Y., 



vol. 5, pt. 



1, p. 143, 



Chemung 



Gr. 



e 1 on gata, 



Hall. 1884, 



Pal. N. Y., 



vol. 5, pt. 



1, p. 141, Chemung Gr. 



eucrate, Hall, 1884, Pal. N. Y., vol. 5, pt. 



1, 133, Chemung Gr. 

 eudora, Hall, 1884, Pal. N. Y., vol. 5, pt. 



1, p. 138, Chemung Gr. 

 eugenia, Hall, 1883, Pal. N. Y., vol. 5, pi. 



23, figs. 17-20, Chemung Gr. 

 expansa, Hall, 1884, Pal. N. Y., vol. 5, pt. 



1, p. 152, Chemung Gr. 

 falcata, Hall, 1884, Pal. N. Y., vol. 5, pt. 



1, p. 136, Up. Chemung Gr. 

 galene, Hall, 1884, Pal. N. Y., vol. 5, pt. 



1, p. 142, Chemung Gr. 

 gibbosa, Hall, 1884, Pal. N. Y., vol. 5, pt. 



1, p. 149, Up. Chemung Gr. 

 lata, Hall, 1884, Pal. N. Y., vol. 5, pt. 1, 



p. 145, Up. Chemung Gr. 

 lobata, Hall, 1884, Pal. N. Y., vol. 5, pt. 1, 



p. 150, Up. Chemung Gr. 

 perlata, Hall, 1884, Pal. N. Y., vol. 5, pt. 



1, p. 147, Up. Chemung Gr. 

 proto, Hall, 1884, Pal. N. Y., vol. 5, pt. 1, 



p. 129, Chemung Gr. 

 protoformis, Walcott, 1885, Monogr. U. S. 

 Geo. Sur., vol. 8, p. 235, Subcarbon- 

 iferous. 

 salamanca, Hall, 1884, Pal. N. Y., vol. 5, 

 pt. 1, p. 131, Chemung Gr. 



