NATURAL SCIENCES OF PHILADELPniA. 181 



Compared with foreign forms, this shell seems to be most nearly 

 like the extremely narrow and elongated variety of S. duplicosta. 

 Phillips, as illustrated by Mr. Davidson's figure, 8, pi. iv., Mongr. 

 British Carb. Brachiojioda. It is much more gibbous, however, 

 with a decidedly more prominent and more angular mesial sinus, 

 while its surface granules and minute striffi serve to distinguish 

 it. Although its mesial fold has a vei'y angular appearance, a 

 careful examination shows it to be very slightly flattened, or even 

 faintly furrowed along its prominent middle; while there is some- 

 times a faint indication of a slightly more prominent rib in the 

 middle of the angular sinus of the other valve. 



Locality and jDOsition. Young County, Texas ; where it was 

 foiind hy Mr. H. E. Roessler associated with Coal-measure fossils- 



I have never seen it from any of the western localities north of 

 Texas. 



CAMPELOMA (MELANTHO) MACROSPIRA, Meek. 



Shell attaining a large size, thick and strong, elongate-subovate; 

 spire much elevated; volutions five, convex but not rounded, in- 

 creasing gradually in size, excepting the last one, which is more 

 abruptly enlarged, oblique, and somewhat produced below; suture 

 stronglj' defined; aperture ovate, nearly or quite half the length 

 of the shell ; inner lip thick and more or less reflected in the adult, 

 but leaving uncovered a rather distinct umbilical impression. Sur- 

 face with only moderate]}^ distinct marks of growth. 



Length of an adult, 1.10 inches; breadth, 1.10 inches. 



Specimens of this species have been brought by various explor- 

 ing parties, during the last eight or ten years, from the Bear River 

 country, Utah; but always in too imperfect a condition to show 

 their characters clearlj', until some recently brought in. These 

 show it to resemble, when not distorted, an abnormally elongated 

 specimen of C. {Melanfho) integra, Say, figured by Mr. Binney in 

 his Smithsonian monograph, part iii., p. 49, excepting that its 

 volutions are less convex, its spire a little narrower below, and 

 its bod}^ volution and suture more oblique. Its inner lip is also 

 less oppressed to the columella, so as to leave a decided larger 

 and deeper umbilical impression. It is likewise a thicker, stronger 

 shell than any of the varieties of C. decisa I have ever seen, being 

 as thick as C. ponderosa^ if not thicker. 



isn.] 



