o/' 



NEW YORK STATE MUSEUM 



overlapping less than one third of length, inclined at an angle of about 40°; 

 proximal part of outer wall excavated, distal part of outer edge very con- 

 vex, aperture vertical to axis of theca, apertural margin concave. Inter- 

 thecal excavation deep (nearly two fifths of width) and as long as free part 

 of theca. 



Formation and localities. Lapworth has described this species as one 

 of the forms of the British Glenkiln beds and later on recognized jt in col- 

 lections from Dease river in British Columbia and various places in Quebec 

 (Griffin Cove, Little Mechin river, Cove Fields, etc.). 

 We have observed it in shales of the Normanskill zone 

 from Glenmont, Albany co., Mt Moreno, near Hudson 

 W (where it is very common in one layer) and Speigletown. 

 f jL Lapworth's manuscript report does not record it from 

 Stockport, Columbia co. We have also observed speci- 

 mens which though badly compressed and extenuated, 

 quite evidently belong to this type, in collections from 

 Silver Peak Quadrangle, Nevada. The range of this 



F 'g- 3*5. 316 Diplo- • l 1 1 at 1 -11 1 1 / t\ 



graptus eugiyphus form mav begin below the JNormanskill shale (at Uease 



JLapworth. Portions of J <-> 



river), and extend through the same into the Upper 

 Dicellograptus zone (Cove Fields). 



Remarks. This species is easily recognized by its very long slender 

 form and the wide intervals between the thecae. The latter are only to a 

 small part due to a smaller overlap of the thecae and mostly to the deep 

 excavation of the outer wall in the proximal part [see text fig. 315], which 

 allows the shale to enter between the thecae and produces a concave outline 

 of the proximal part of the theca. Also the convex outline of the distal 

 part of the theca and the concave apertural margin are characteristic features 

 of 1 ) . e u g 1 y p h u s. 



Lapworth states the form to be destitute of lateral spines, but in 

 one of our specimens from Mt Moreno two very thin, curved spines are 

 observable. 



