524 GEOLOGY OF OHIO. 



by a distinct but not deep groove. The fixed cheek and anterior portion 

 of the head continues the low curvature of- the glabella, and the anterior 

 border of the head is denned rather by its upward curvature than by any 

 distinct defining groove. The glabella was 3.8 mm. long; the distance 

 from the occipital groove to the anterior border was 4.7 mm. and including 

 the anterior border, 5.1 mm. At the Soldiers' Home the specimens 

 occur in the upper third of the limestone but beneath the shah- portion- 



Cybhaspis Clintonensis, Foerste. 



Plate 27, Fig. 5 ; Plate 31, Fig. 22). 



This species was described in the Proceedings of the Boston Society 

 of Natural History, 1889, from Brown's Quarry, and the occurrence of 

 the same species at Anticosti, and Cumberland gap, Tennessee was noted. 

 Since then one glabella has been found in the upper third of the Clinton 

 limestone at Huffman's Quarry, and various glabellas and two more per- 

 fect heads occurred in the "Orthoceras block" at the same locality. The 

 latter enable us to define the specific characters of the species much 

 more clearly. 



The glabella shows the usual pair of postero-lateral lobes. Anterior 

 to the glabella, separated only by a narrow groove, lies the flattened, thick- 

 ened anterior border. Both groove and border are continued parallel to 

 the margin of the free cheek, being met at the postero-lateral angle by a 

 similar border and inner groove running parallel to the posterior margin 

 of the head. The free cheeks are continued beyond this angle as a spine. 

 The e}"es are boldly convex and very large for such a small species A 

 small but very perfect specimen had a head almost 5 mm. long, and 7 

 mm. wide. The glabella alone was 3.6 mm. long, and just anterior to 

 the postero-lateral lobes it was 2.7 mm. wide A line joining the most 

 exterior points of the eyes measures 4.6 mm. The eyes are 1.7 mm. 

 long. The postero-lateral spines project at least 2 mm. beyond the pos- 

 terior margin of the head. 



With these data it now becomes easy to distinguish this species from 

 Cyphaspis Christyi, Hall of the Niagara group. In that species there is 

 also a narrow groove anterior to the glabella, anterior to which is a broad 

 raised area which, when the real border is broken off, ab}^ no means uncom- 

 mon occurrence, very much resembles the actual border of the Clinton spe- 

 cies. Anterior to this area in the case of the Niagara species, separated by a 

 deeper groove, comes the real anterior border of the head. The Clinton 

 species was probably the progenitor of the Niagara form, by a gradual 

 widening of the groove between the anterior border of the head and the 

 glabella into an anterior area. This groove in the case of the "Orthoce- 

 ras block" specimens from the base of the Clinton, was very narrow. 

 In the Brown quarry specimens it was wider but still fairly narrow. 

 From the upper red tinged limestone at Huffman's quarry come the spec- 

 imens with the widest grooves; length of head in one case, 5.2 mm.; of the 



