j6 NEW YORK STATE MUSEUM 



rather sharp and deep retral curve at the summit of the whorl, indicating 

 the position of the apertural notch. 



Dimensions. Two specimens, both of which were collected at Roches- 

 ter, have a greatest width of 38 mm, and the body whorl near the aperture 

 has a hight of 1 8 mm. 



Observations. No species of similar habit and expression has been 

 described from the Guelph fauna. Billings's two species, Straparollus 

 h i p p o 1 y t a and S. daphne, from the dolomites at Gait are small shells 

 with elevated spires ; S. m o p s u s Hall 1 from the Racine limestone at Racine 

 is smaller and has cylindric volutions ; its surface markings are not known ; 

 S. niagarensis Hall & Whitfield 2 has revolving ridges on the whorls. 

 The resemblance of the species is however extremely close to certain 

 expressions of E. gotlandicus Lindstrom. 3 Lindstrom has maintained 

 that individuals of a given species of Euomphalus may have their whorls 

 contiguous throughout or be evolute in varying degree. Hence to this spe- 

 cies, E. g o 1 1 a n d i c u s, he has referred a series presenting all phases in 

 the unwinding of the whorl, thus embracing within the same species the 

 conditions typical of both Euomphalus and Eccyliomphalus. With the 

 involute expression of this species the agreement of E. f a i r c h i 1 d i is so 

 close as fully to justify identification were the evolute condition of the 

 species eliminated, for this is not expressed in any of the specimens before 

 us. We are however disposed to follow Lindstrom's valuation of the genus 

 Euomphalus and have hence employed the designation in preference to Mr 

 Ulrich's equivalent construction of the later term Eccyliomphalus and the 

 common and freer employment of Straparollus, in which the whorls are 

 impressed and the evolute condition less complete. 



Named for H. L. Fairchild, professor of geology, University of 

 Rochester. 



! N. Y. State Cab. Nat. Hist. 20th An. Rep't, p. 342, pi. 15, fig. 21, 22. 

 "Pal. Ohio. 1875. 2:144. 



3 The Silurian Gastropoda and Pteropoda of Gotland, p. 139, pi. 13, fig. 19-31, spe- 

 cially fig. 20-22 



