•100 A. HYATT — GEOLOGY OF THE TAYLORVILLE REGION. 



species of Tnoceramus) and a fragmenl of an ammonite of the genus Peri- 

 sphinctes. The Tnoceramus of the Jura is not so large in the Lias as in the 

 Oolite and these fragments appeared, therefore, to have belonged to 

 shells al least as old as the Oolite. The specimen of Perisphinctes may 

 prove to be identical with some species found below. It is probable, 

 therefore, that this bed belongs, as in fact is indicated by the geology, to 

 the upper part of the Mormon sandstone. On the other hand, the fact 

 that one out of the three species was new to the fauna of the Mormon 

 sandstone justifies a provisional separation under a different title on 

 biologic "rounds. Even if not sustained by future work, this distinction 

 will serve a good purpose if it succeed in calling the attention of col- 

 lectors in the same or other localities to facts that might otherwise escape 

 t heir notice. 



Upper Jura or Malm : Bicknell Sandstone ( Trigonia Bed). — The fauna 

 of the Bicknell sandstone is not so rich in species as are the Mormon 

 and Hardgrave sandstones and the Thompson limestone, nor are the fos- 

 sils so plentiful. The character of the rock in the surface exposures 

 found by the party made it almost impossible to get out large specimens 

 in perfect condition. Nevertheless, a sufficient number of molds of sev- 

 eral large species of Trigonia (T. obliqua and T. plumasensis) and some 

 well preserved specimens of Gryphasa bononiformis were secured; allot' 

 which are more or less characteristic of the youngest faunas of the Jura 

 in Europe. 



The remains of the anmionitiiue are fragmentary, but those that were 

 found certainly indicate a somewhat older fauna than the species above 

 named. There are a number of the molds of Rhacophyllites with the 

 internal septa partly preserved, a fragment of a Reineckia, two rather 

 pool- molds of Macrocephalites (f), and several fragments of Perisphinctes.. 

 These form an association which gives strong support to the provisional 

 opinion that the faun:! is really synchronous with that of the Callovian, 

 the oldest fauna of the upper jura, or Malm, in Europe. The specimens 

 of Chemnitzia are molds of a very large shell, but unluckily do not show 

 the aperture. The only species in Europe which appears to be a close 

 ally of this is also from Callovian. 



The list below gives a very inadequate idea of the fauna., since none 

 of the belemnites or animonitinae can he directly compared with Euro- 

 pean species on account of the need of more perfect specimens and are, 

 with one exception, not mentioned. There are also a Large Nerinea and 

 a \\-\\ species of pelecypoda and brachiopoda, which were not considered 

 important in this preliminary notice; 





