226 Observations upon the Geolog-y and Paleontohg-y 



at present to discuss, but a suggestion may not be out of 

 place. Admitting that some of the species found in the 

 lower beds have been identified with those of the Chemung 

 group of New York, it settles beyond question their geo- 

 logical equivalency, but does not necessarily prove that 

 they were contemporaneous. Indeed, it seems probable 

 that they were not so, by an interval of the time that it 

 would take the species to migrate that distance. May it 

 not, therefore, be inferred that the species originated at the 

 east, and were migrating westward during the time that 

 the bottom of the Chemung seas was sinking, and 

 receiving upon it the deposit of the Old Red Sandstone, — 

 thus making these Devonian rocks equivalent to the Che- 

 mung of New York, and contemporaneous, at least in part, 

 with the Old Red of the Catskill Mountains ? 



Descriptions of seven neiv Species of Brachiopoda from the 

 Chemung" Rocks at Burlington, Iowa. 



KHYNCHONELLA PUSTULOSA (Whitk.) 



Shell subtrigonal, or subglobose, front broadly rounded, 

 or slightly flattened, sides flattened and meeting at the 

 beak at nearly a right angle. Dorsal valve much more 

 convex than the ventral valve, which is usually some- 

 what depressed. Beak closely incurved. Highest part, 

 near the front margin. Beak of ventral valve prominent, 

 acute, and considerably incurved ; foramen triangular. 



Surface marked by from twelve to sixteen strong, some- 

 what rounded plications, three of which are usually moder- 

 ately depressed on the ventral valve, and four elevated on 

 the dorsal valve, forming the mesial fold and sinus, which 

 are not observable much more than half the length of the 

 shell. Along the centre of each of the plications, for a 



