398 The Ohio Journal of Science [Vol. XIX, No. 7, 



figured from the Rogers Gap member of the Cynthiana formation, in 

 Jour. Cincinnati Soc. Nat. Hist., vol. 21, 1914, pi. 1, fig. 18; see also 

 Fig. 18 A, on Plate XIX, accompanying the present paper). "The 

 neck ring bears a tubercle on the middle of the posterior margin suggest- 

 ing an incipient spine; this tubercle, however, is not larger than those 

 on the front of the glabella. " 



An entire individual of this species was figured by Clarke 

 in 1894 (Geol. Minnesota, vol. 3, pt. 2, p. 727, fig. 44), from 

 the Trenton limestone at Trenton Falls, New York. At my 

 request Dr. Rudolf Ruedemann reexamined this specimen 

 and sent the description given above. 



Those parts of Figure 8, cited above, which are not dotted, 

 were added to indicate the relative position of the glabellar 

 furrows on the glabella and were not included in Dr. Ruede- 

 mann's sketch. These parts may require modification, especially 

 in connection with the neck ring. 



Pterygometopus carleyi-rogersensis, Foerste. 

 Piatt' XIX, Figs. IS A, B. 



1910. Dalmaniles carleyi-rogersensis, Foerste, Bull. Sci. Lab. Denison Univ., 



vol. 16, p. 85. 

 1914. Dalmaniles achates, Foerste, Jour. Cincinnati Soc. Nat. Hist., vol. 21, p. 147, 



pi. 1. fig. IS. 



So far no difference is known between the variety rogersensis, as 

 found in the Rogers Gap division of the Cynthiana formation, and the 

 typical forms of the species carleyi, from the Fairmount division of the 

 Maysville formation, except in size, the Rogers Gap speciinens usually 

 being larger. In Dalmanites carleyi the first pair of glabellar furrows 

 diverges at an angle of about 140 degrees, the curvature being slightly 

 sigmoid, at first toward the front and then more lateral. The second 

 pair of grooves curves moderately backward and sometimes tenninates 

 before actually reaching the dorsal furrows limiting the glabella laterally. 

 The third pair of glabellar furrows curv^es so as to be directed slightly 

 backward at first and then more or less forward. The corresponding 

 parts of the neck furrow have a similar curvature. The frontal lobe 

 of the glabella is remarkably wide and short, and has a transversely 

 rhomboidal outline. A slightly rhomboidal appearance is characteristic 

 of the anterior outline of the cephalon which tends to be slightly angular 

 immediately in front of the center of the frontal lobe and also in front 

 of the lateral part of the visual surface of the eye. The visual surface 

 (Plate XIX, Fig. 18 B) is composed of 21 or 22 vertical rows of facets, 

 the maximum number of facets in the middle rows being about 11 or 12. 

 In Dalmanites carleyi the coarser granules are confined chiefly to the 

 frontal lobe and to the median parts of the glabella; a few occur on the 

 first pair of glabellar lobes, but elsewhere they usually are rare or absent. 



