248 THE DEVONIAN OF MISSOURI. 



Family Rhynchospiridae 



Genus Rhynchospira Hall 



Rhynchospira attenuata sp. nov. 



Plate 65, figure 3 



Description — The collection contains a single nearly complete pedicle valve of a 

 Rhynchospira, which belongs to an undescribed species. Shell of medium size, longi- 

 tudinally subovate, postero-lateral margins converging gradually to the beak. The 

 dimensions are: Length 14 mm., width 11 mm. Beak elongate, acute, apex perforated 

 by a round foramen. 



Surface marked by 10 to 12 simple, coarse, angular plications. 



Brachial valve unknown. 



Remarks — This form is unlike any described species of the genus in the extremely 

 elongate and attenuate beak, and the more coarsely plicate surface. 



Horizon— Upper beds. 



Holotype No. 27497, Walker Museum. 



Trematospira multistriata (Hall) 



Plate 65, figures 4, 5 



1857. Spirifer multistriata Hall, Tenth Ann. Rept. N. Y. State Cab. Nat. Hist., p. 59, 



figs. 1-6. 

 1859. Trematospira multistriata Hall, Nat. Hist. N. Y. Pal., vol. 3, p. 209, pi. 24, 



figs. 3a-3f ; pi. 28a, figs. 5a-5f. 

 1900. Trematospira multistriata Clarke, Mem. N. Y. State Mus., vol. 3, No. 3, p. 43, 



pi. 6, figs. 1-4. 

 1913. Trematospira multistriata Schuchert, Geol. Surv., Md. Low. t)ev., p. 428, pi. 

 73, figs. 3, 4. 



Description — Shell of medium size, transversely oval in outline, cardinal extremities 

 rounded. The dimensions of two separate valves are: Pedicle, length 19 mm., width 

 25 mm.; brachial, length 18 mm., width approximately 22 mm., the greatest width a 

 little in front of the hinge line. 



Pedicle valve moderately convex, with an ill-defined mesial sinus, which is broad and 

 shallow at the anterior margin, but towards the beak becomes narrow and almost 

 obsolete. Beak small, blunt, incurved over that of the opposite valve; apex pierced by 

 a round foramen. 



Brachial valve slightly more convex than the pedicle, the middle portion elevated 

 into a scarcely perceptible fold which broadens anteriorly. Beak small, closely incurved 

 below the other. 



Surface of both valves marked by numerous prominent, angular, radiating plica- 

 tions; these bifurcate at regular intervals, each one usually twice in passing from the 

 beak to the anterior margin, hence giving the surface a fasciculate appearance. Con- 

 centric lines of growth across the shell. 



Remarks — This characteristic Helderbergian form is represented in the Little 

 Saline fauna by a few separate valves but among the specimens studied none attain 

 the large size of the full-grown New York examples as figured by Hall. In size, and in 

 the number and coarseness of the plications, they seem to be more closely allied with 

 the southern examples figured in the Maryland reports. 



Horizon — Upper beds. 



Figured specimens No. 27496, Walker Museum. 



