COAL-MEASURE SPECIES. 341 



escutcheon can not be clearly seen, though it is evident enough that they 

 exist. In general appearance it strongly recalls certain forms of Cras- 

 satella. Compared with Astartella vera, Hall (Iowa Report, I., part 2, 

 figs, la, b), it will be seen to differ in having its beaks decidedly less 

 prominent, less tumid, and farther from the anterior margin, while its 

 posterior dorsal outline is straighter, and its concentric ridges more 

 numerous, more prominent, and more regularly arranged. In its surface 

 markings it more nearly resembles Astartella concentrica (=Nuculites con- 

 centricus, Conrad, Jour. Acad. Nat. Sci., Philad., VIII., pi. 6, fig. 19, 1839), 

 from the Coal Measures of western Pennsylvania, but it is a more depressed, 

 elongated shell, with less elevated and less nearly terminal beaks. It is 

 barely possible that our shell may be a variety of one or the other of 

 the species with which I have compared it; but with the only means of 

 forming an opinion on this point now at hand, I can but regard it as a 

 distinct species from both. 



I have seen a specimen in Dr. Hayden's collections, from near Virginia 

 City, Montana, that I could not distinguish from this, though it came, 

 with some other Coal-Measure fossils, from beds apparently of the age 

 of the Chester limestone. 



Locality and position : Newark, Ohio. From the Coal Measures. 



Astartella varica, McChesney. 



Plate 19, fig. 2. 



Astartella varica, McChesney (1860) ; Descriptions of ISTew Palaeozoic Fossils, 55, and 

 (1869) Trans. Chicago Acad. Sci., I., 42, pi. 2, fig. 7. 



I merely refer this shell doubtfully to the above cited species, not hav- 

 ing had an opportunity to compare it with authentic examples of that 

 form. So far as can be determined, however, from Prof. McChesney's 

 figure and description, it seems to agree quite closely with his species 

 in outline, being only a little more depressed, yet its concentric ridges 

 appear to be less sharply elevated, and it is possible that a direct com- 

 parison might show other differences. 



Locality and position : Coal Measures, at Newark, Ohio. 



Astartella (undetermined sp.). 



Plate 19, fig. la, h. 

 I have been unable to decide in regard to the specific relations of this 

 shell. At one time I thought it might be a variety of A. vera, Hall, but 



