182 ROYAL SOCIETY OF CANADA 



middle piece of the head is not quite so wide, and that some examples 

 have shallow furrows on the glabella ; some, however, have none, and 

 even the ocular fillet is nearly effaced. 



A pygidium found with this species has all the characters ascribed 

 by Mr. VValcott to that of P. Adamsi. 



Sculpture. — The surface has a velvety appearance, due to the minute 

 tubei'cles that cover the surface, and are distinguishable with a lens. 

 Some heads show closely set strife just visible to the naked eye, radiating 

 from the glabella and ocular fillet to the anterior marginal furrow, such 

 as are found in Anomocare (Ptychoparia) microphthalma and Ftycho- 

 paria striata ; these are most distinct on the under surface of the test. 



Size. — Length of the head shield, 8 mm. ; width of the middle piece 

 at the eyes, 9 mm. : at the posterior angles, 12 mm.. Length of pygidium. 

 3 mm. ; width, 7 mm. 



Horizon. — Conglomerate limestone bands in the gray shales. 

 Common. 



Narrow form. (PI. III., figs. 2 a and b.) 



Heads of the length of 5 mm. show persistently considerably less 

 width than the full grown heads, and among some of the larger heads are 

 some that are considerably narrower than others, but in other respects 

 agree with the normal form. Similar differences have been noted in the 

 Ptychopariœ of the old sub-faunas, and are only varietal or sexual. 



SOLENOPLEUEA, Angelin. 

 Solenopleura arenosa, Billings sp. (PI. IV., fig. 10.) 



Conocephalites arenosus, Bill., Palseoz. Foss., voL i., p. 15, fig. 18. 

 Conocephalites arenosus, Wale, U. S. Geol. Surv. Bull. 30, p. 195. 



Original description by Billings : 



" Glabella conical, about three-fourths the length of the head ; con- 

 vex, well defined by the dorsal furrows all around ; neck furrow all across ; 

 posterior glabella furrows represented by obscure undulations, which 

 appear to be directed obliquely backward from near the middle length to 

 near the neck furrow. Front margin with an elevated rostrum and 

 transverse groove, the latter passing at about one-third from the front of 

 the glabella. Ocular ridge well defined. 



" Length of head, 3^ lines ; of glabella, 2i lines ; width of glabella 

 at the base, 1| lines ; at one-third of the length from the front, ]^ lines. 



" The character of the impression taken to be the posterior glabellar 

 furrows are not well ascertained." 



