130 Monograph of the Crustacea of the Cincinnati Group. 



Pygidium small, and with its mesial lobe composed of about three 

 seginents ; lateral lobes consisting, apparently, of about three or four 

 segments, each of which terminates in an acute spine, the lateral ones 

 of which are larger than the others, and curved backward. 



Entire surface, comparatively, rather coarsely granular, the granules 

 being larger on the head than elsewhere ; while on each of the pleurse 

 a larger granule or very minute tubercle occurs, at a point about half 

 way out to the knee, or geniculation, at which latter point there is also 

 some ai:)pearance of another, thus making two rows of these coarse 

 granules along each lateral lobe. 



Entire length, exclusive of the spines of the pygidium, about 0.25 

 inch ; length of head, 0.08 inch ; breadth, exclusive of lateral spines, 

 0.15 inch; breadth between eyes, 0.10 inch ; length of thorax, about 

 0.11 inch ; breadth of same antei'iorly, exclusive of the extended ends 

 of the pleurse, 0.14 inch. 



The specimen above described by Prof. Meek, belonging to Dr. C. 

 A. Miller, was found at Ballfiice Creek, below Sedamsville. I found a 

 specimen 0.40 inch in length back of Plain ville. I also found speci- 

 mens in the excavation for Columbia avenue, about 160 feet above low 

 water-mark. Its range extends at least from low water-mark to 250 

 feet above and probably much more. It is, however, regarded as a rare 

 fossil, esi^ecially in a good condition. 



Acidaspis ceralepta — (Anthony, 1838). 



This species is known only from the pygidium, which is sub-semi-cir- 

 cular in outline, and has two long, divergmg spines, with six short 

 digitations between them, and three on each posterior lateral margin. 



Fragments of the margin of a cephalic shield, having much shorter 

 spinous processes than the Acidasjns Cincinnatiensis, may belong to this 

 species. It has been urged that the cephalic shields having a project- 

 ing spine from the base of the glabella, which are found about Cincin- 

 nati, belong to two different species; if so, one of them may belong to 

 this species, the other one we know belongs to the Acidaspis Cincin- 

 natiensis. 



Acidaspis Cincinnatiensis — (Meek) . 



This species was described from a pygidium by Prof. Meek, on page 

 167, and, engraved on plate 14, fig. 3, of the Ohio Paleontology. 



From a specimen in the cabinet of Dr. H. H. Hill, I am enabled to 

 throw some more light upon it. The specimen shows but little of the 



