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NEW YORK STATE MUSEUM 



area subserves the purposes of articulation, though these processes are not 

 to be regarded as hinge teeth. We believe with Beushausen that the 

 affinities of Euthydesma were doubtless with the Cardiolidae, that is with 

 such of them as have been already here described, and the presence of the 

 peculiar structure mentioned does not militate against this interpretation. 



Euthydesma subtextile Hall 



Plate 9, fig. 8-17 



As t arte subtextilis Hall, Geology of New York ; rep't on fourth dist. 1843. 



p. 245, fig. 6 

 Cardiomorpha subtextilis Hall, Preliminary Notice Lamellibranchiata. 1870. 



Pt 2, p. 93 

 Cardiomorpha textilis and u n d u 1 a t a, Paleontology of New York. 1883. 



v. 5, pt 1, plates and explanations, pi. 63, fig. 11-16 

 Euthydesma subtextile Hall, Paleontology of New York. 1885. v. 5, pt 1, 2, 



p. 385, pi. 63, fig. 1 1-16 ; 93, fig. 28, 29 

 cf. My til area beyrichi Holzapfel, Palaeontographica. 1882. 28:257, pi. 48, 



fig. 8, a, b and 

 Euthydesma beyrichi Beushausen, Abhandl. der konigl. Preuss. geolog. 



Landesanst. N E. 1895. Heft 17, p. 317, pi. 38, fig. 7, 8 



This shell has been quite fully described and delineated in the Paleon- 

 tology of New York, and hence its characters do not require full explication 

 here. 



The species is peculiarly localized, having been found in New York 

 only about the shore of Lake Erie, where it appears to be very common at 

 certain localities. In external aspect it is somewhat variable, at times being 

 almost smooth or with fine concentric striae ; usually bearing strong and 

 low oblique ridges on the surface 1 and generally on both valves two or 

 more strong ribs extending along the hinge line and obliquely from the 

 beak to the posterior extremity. These are present in the original of the 

 figure 13 cited in the accompanying footnote, but have been omitted in the 

 drawing Good sculpture casts show fine concentric lines, distant in the 



•In the specimens represented in figures 13 and 14 on plate 63, Pal. N. Y., loc. a'/., the 

 undulations there appearing as concentric with the growth lines are actually slightly 

 oblique. 



