426 The UrPKit Devoxiax Deposits of Maryland 



one near the top of (lie Ithaca be(k. This zone may correspond to the beds 

 containing the Ithaca fauna in central Xew York. It does not seem 

 possible to correlate these horizons precisely at present, altliougli the oc- 

 currence of these species in Mar}'land is of interest. 



lAorlnjnclius ijlohiiUforme Zone. — H. 8. "Williams has described a 

 fauna from east-central New York to which he has ap[)lied the name 

 Liorhynchus g'iobuliforme fauna from the abundant development of that 

 species in it. He says that " the Ithaca fauna as a whole may be called 

 the Spirifer pennatits var. posterns fauna M-hich on passing eastward is 

 separated into three distinctive paleontological zones, the H^ Paracyclas 

 liraia zone, H^ Spinfer wemstriaJls zone, W Liorlnjiirhus (jlobiiJlfonne 

 zone." ' He further states that the latter zone occupies a higher strati- 

 graphic position than does the Ithaca fauna of central Xew York, cor- 

 relatinor the beds containing it with the basal strata of the Enfield mem- 

 ber of the Portage of New York. He thus manifestly regards the Lior- 

 hynchus globuliforme fauna as a later phase of the Ithaca fauna which is 

 restricted to east-central New York. Many characteristic species of the 

 Ithaca fauna of central New York are present in it including Spirifer 

 mucronatus var. posterns, Pugnax pugnus var. alius, Schizophoria slri- 

 atula, ProducteUa speciosa, Cyrtina lianiVtonensis, Stroplwodonta 

 demissa, and Leptustrophia interstrialis. It contains, however, Spirifer 

 {Delthyris) mesacostalis Mhich makes its first appearance in the Ithaca 

 region in the Tropidoleptus fauna overlying the Ithaca beds. 



The Liorhyjichus globuliforme fauna of Maryland occupies the ujiper 

 part of the Ithaca beds and bears a marked resemblance to the fauna of the 

 same name in Ke^v York as shown by its stratigraphic position and by 

 its dominant species and is probably to be correlated with that fauna; 

 but differs, both in its purer Ithacan character, and in lying below the 

 zone of Spirifer (Delthyris) mesacostalis. The latter species makes its 

 first appearance in the overlying Tropidoleptus carinatus fauna in Mary- 

 land, as it does in central New York. These facts suggest that the 

 Liorhynchus globuliforme fauna of Maryland may occupy a somewhat 

 lower stratigraphic position in ]\Iaryland than in east-central New York. 



' Folio 1G9, U. S. Geol. Survey, 1909, p. 6. 



