1 74 Natural History Bulletin. 



inadequate as the fragments of leisure at the disposal of men 

 doing full work in other directions, to secure in reasonable 

 time anv very satisfactory outcome of investigation. In the 

 absence of a Natural History Survey, supported and encour- 

 aged by the state, it is our purpose to make such progress as 

 may be possible, even though the final summing up of results 

 is likely to be long delayed. 



In this paper two distinct types of Straparolli are illustrated 

 — one, represented by a species from the Devonian, and 

 another, represented by tw^o species from the Upper Silurian. 

 As recently emphasized by Keyes,' the shells of this group 

 present such complete intergradation as to obliterate the dis- 

 tinctions between the proposed genera, Strafarolhis^ Euom- 

 ■phahis^ and Phanerotnuis or EccyliompJialus, and therefore in 

 this paper the generic name StrafaroUus is employed for both 

 types. 



TEREBRATULA, Llhwyd. 

 Terebratula (^Cryptoxella) iowexsis, n. s. 



PLATE III., FIGS. 4 a, b. 



Shell large, ovate, widest at or below the middle, adult 

 specimens very convex, greatest convexity a short distance in 

 front of the umbo; front margin regularly rounded, truncate 

 or slightly sinuate. Dorsal valve convex, curving gradually 

 in all directions from a point situated at a variable distance 

 behind the middle of the valve. Ventral valve, like dorsal, 

 sloping from a point behind the middle line, the curvature in- 

 creasing most rapidly tow^ard the beak; beak only moderately 

 incurved, perforated by a relatively small foramen; cardino- 

 lateral slopes rounding gradually, without the usual subangu- 

 lar ridge toward the deltidial plate; deltidial plate wide, its 

 sides meeting beneath the foramen in an obtuse angle; mus- 



I Keyes, Lovjer Carbonic Gasteropoda from Burlington, lo-va. Proceedings 

 Academy of Natural Sciences of Philadelphia, 1889, p. 291 ; and Certain Forms 

 oj Straparollus from Southeastern lozva, American Geologist, Vol. V., April, 

 1890, p. 194. 



