F. R. Coirper Reed — Salterns Undescribed Species. 257 



Kemarks. — It is not very profitable to compare this poorly defined 

 species with others. The only form of Goniophora known to me 

 with similar radiating ribs on the anterior lower half of the shell 

 only and concentric ridges above and below the carina, is G. truncata, 

 Hall/ from the Hamilton Group of New York. 



MODIOLOPSIS COMPLANATA (SoW.). 



1851. Modiolopsis complanata (Sow.), McCoy: Brit. Pal. Foss., p. 266. 

 1873. Mocliolopsis pJanata, Salter: Cat. Cam. Sil. Foss., p. 182 [b 71-3). 

 1891. Modiolopsis planata, "Woods: Cat. Type Foss. AVoodvr. Mus., p. 81. 



The specimens which McCoy named and described (op. cit. supra) 

 as M.. complanata (Sow.) were renamed M. planata by Salter, though 

 in the margin of his Catalogue (loc. cit.) he puts M. complanata with 

 a query after it. I do not see sufficient reason to doubt the accuracy 

 of McCoy's identification, and therefore Salter's specific name planata 

 must be dropped. 



MoDioLOPsis MiMUS, Salter. (PI. XVI, Fig. 3.) 



1873. JL/tiliis mimus, Salter : Cat. Camb. Sil. Foss. Woodw. Mus., p. 182 {b 141). 

 1891. Mi/tilus minimus, Woods: Cat. Type Foss. Woodw. Mus., p. 82. 



The name of this species is printed mimus in Salter's Catalogue, 

 both on p. 182 and in the index, p. 200. On the back of the tablet 

 bearing the specimen the name minimus was found written in pencil, 

 and Mr. Woods adopted this in his Catalogue. There is only one 

 specimen of the left valve {h 141), and it comes from the Upper 

 Ludlow of Lesmahagow. 



Diagnosis. — Shell inequilateral, obliquely elongate, obtusely 

 pointed. Body narrow, slightly curved, convex, especially near 

 beak. Beak anterior, terminal, small, pointed, convex. Posterior 

 portion of shell rather depressed and flattened, but not sharply 

 marked off from body of shell. Ventral margin short, subacuminate. 

 Posterior margin almost vertical, gently rounded. Hinge-line straight, 

 nearly the width of shell, at angle of 60° to oblique axis. 



Surface marked with concentric growth-lines. 



Measurements. mm. 



Length along oblique axis ... ... ... ... ... 16 



Width along hinge-line ... ... ... ... ... 9 



Length from hinge-line to ventral margin ... ... 12 



Remarks. — This species bears some resemblance to the Bala form 

 Modiolopsis pyrus, Salter,'- but the hinge-line is relatively rather 

 longer, the beak more acuminate and terminal, and the posterior 

 portion of the shell larger. Some American species of Leptodesma 

 from the Chemung Group ^ seem to bear a considerable resemblance 

 to M. mimus. 



Orthonota (?) HuGHESi, Salter. (PI. XVI, Figs. 4, 5.) 



1873. Ctemdonta Hnghesi, n.sp., Salter: Cat. Camb. Sil. Foss. Woodw. Mus., 



p. 82 (ff 979). 

 1891. Ctenodonta Hughesi, Woods: Cat. Type Foss. Woodw. Mus., p. 74. 



1 Hall: Palfeout. N.Y., vol. v (1883), p. 13, pi. xliv, figs. 1-5. 



- Mem. Geol. Surv., vol. iii, 2nd ed. (1881), p. 552, woodcut xii, fig. 1. 



3 Hall: Pal. N.T., vol. v, pt. 1, pi. xci, figs. 23-5. 



DECADE IV. VOL. IX. — NO. VI. 17 



