EARLY DF.VONIC HISTORY OF NEW YORK AND EASTERN NORTH AMERICA 95 



DESCRIPTION OF THE FAUNA OF THE CHAPMAN SANDSTONE 

 Asterolepis clarkii Eastman 



See N. Y. State Mus. Mem. 10. 1907. p. 40, pi. 7, fig. 7, 8 



Locality. Presque Isle stream. 



Spirorbis sp. 



Abundant on dead shells. 

 Locality. Presque Isle stream. 



Homalonotus vanuxemi Hall 



Plate 22, figures 2-6 

 See p. 67 



Homalonotus vanuxemi Hall. Palaeontology of New York. 1859. 3:352, pi- 73, 



fig. 9~'3 

 Homalonotus vanuxemi Hall & Clarke, op. cit. 1887. 7:11, pi. VB 



This species, rare in the Helderbergian (New Scotland beds) from 

 which it was described, but more frequent in the calcareous Oriskany fauna 

 of southeastern New York, is well marked by its highly convex, well" seg- 

 mented pygidium. There is nothing in the structure of the parts before us 

 that suggests any similarity to species of the genus from the transatlantic 

 strata. The parts are wholly without ornament, in which respect the speci- 

 mens are in harmony with other American species and in measurable con- 

 trast to the more prevalent spinous forms of the Coblentzian of Europe and 

 the Bokkeveld beds of South Africa. The pygidium is narrow, relatively 

 slender, with abruptly sloping sides and sharply segmented in the same 

 degree as the pygidium of H. vanuxemi in the Dalmanites dentatus 

 beds of Port Jervis, New York (Oriskany). The head also possesses the 

 rather broad anterior border which characterizes H. vanuxemi. We 

 have had occasion previously to observe that sharp segmentation of either 

 pygidium or head is an index in this genus of early age ; that in later 

 Devonic forms this segmentation is obscured at maturity though it may be 

 apparent -in young stages. 



Locality. Edmunds Hill. 



Phacops cf. logani Hall 



See pt r. p. 118 ; pt 2, p. 18 



This species is represented by a glabella and several pygidia. The 



former shows it to be a normal member of the genus with full coalescence 



of the glabellar lobes and highly pustulose surface. The pygidia have the 



.pleurae divided as in other early species of the genus. Such typical and 



normal Phacopes are extremely rare in Siluric faunas. We have previously 



