332 Systematic Paleontology — Middle Devonian 



fauna. Although P. a-istaia is readil}^ distinguished from P. pipa by the 

 axial row of spines and other less conspicuous differences in perfect speci- 

 mens, the two are often difficult to discriminate in the fragmentary 

 material representing tlicm in the average collection. The glabella figured 

 represents the largest individual observed, its length and breadth are 

 respectively 18 and 24 mm. The genal spines, though not sho\vn in the 

 figure, are indicated by broken bases in the specimen. 



Occurrence. — Romney Formation, Onondaga Member. Twenty- 

 first Bridge; Williams Eoad, Si/o miles southeast of Cumberland; Tonolo- 

 way; Hanging Eock, West Virginia. 



Collections. — Maryland Geological Survey ; TJ. S. National Museum. 



[E. M. Kindle.] 



Phacops cristata var. pipa Hall 

 Plate XLIII, Figs. 16, 17 



Phacops cristata var. pipa Hall, 1888, Pal. N. Y., vol. vii. p. 18, pi. vlllA, 



figs. 5-18. 

 Phacops cristata var. pipa Kindle, 1912, Bull. U. S. Geol. Surv., No. 508, p. 108, 



pi. X, figs. 9, 10. 



Description. — " The essential points of difference between this form 

 and the normal Phacops cristata, are the foUomng: (a) greatly inferior 

 size, (b) absence of the a.xial row of spines, (c) smaller spines at the 

 genal angles, (d) fewer annulations upon the pygidium, (e) smaller num- 

 ber of corneal lenses, varying, as ascertained from measurements of a large 

 number of specimens, from 23 to 45 for each eye." Hall, 1888. 



The variety seems to be abundant and is very generally present in the 

 calcareous shales and argillaceous limestones of the adjacent states of 

 Pennsylvania and West Virginia. It has been observed at but one locality 

 in Maryland. 



Occurrence.— RoMSEY Formation, Onondaga Member. One mile 

 east of Oldtown in cut of Western Maryland Eailroad. 



Collection. — U. S. National Museum. 



[E. M. Kindle.] 



