FOSSILS. 007 



side greater than the length of the axis. Axis wider than the lateral 

 lohes, distinguishable (in casts) from the lohes by a bending of the 

 rihs and a scarcely perceptible depression along that line; annulations 



abruptly prominent; seven on the lateral lobes and nine on the axis, 

 the anterior ones bending Blightly backward at the line of division 

 between the axis and the lateral lube; each successive one bending 

 more and more abruptly till the last one approaches a rectangular 

 turn; the whole curving gently forward at their extremities, and all 

 terminating abruptly before reaching the margin. Behind the seventh 

 annulation the axis is marked by two more simulations, leaving nearly 

 one-fourth of its length smooth. 



This species is described from the casts and impressions of the 

 caudal shield, so that the crustaceous covering is unknown. It is 

 readily distinguished by the broad not prominent axis, the rectangular 

 direction of the annulations on the axis, and their abrupt bending at 

 the lateral furrow. An impression of a few imperfect annulations of 

 the body shows that they are strongly elevated, much more so than 

 in any known American species. Arisaig, coll. J. W. D. 



Fig. 214. — Homalonotus Daivsoni, Head and Pygidium. 



Fig. 215. — Dalmania Logani, Head and Pygidium. 



When Professor Hall described this species, the caudal shield only 

 was known, with some of the segments of the body. Dr Honeyman 

 subsequently found specimens of the head. It has the posterior border 

 nearly straight, the glabella moderately prominent and slightly wider 

 behind than before. It descends abruptly in front, and the frontal 

 margin appears to have risen with equal abruptness in front of the 

 glabella and eyes. The eyes arc large and prominent, and advance 

 into a line with the front of the glabella. Some specimens have the 

 head nearly three inches broad. 



Calymene Blummbachii, var. Caudal shield somewhat semicircular, 

 axis very prominent, marked by about seven annulations, lateral lobes 

 marked by five ribs, the four anterior ones bifurcating. Surface granu- 



