18 PROCEEDINGS OF THE ACADEMY OF [1887. 



The pygidium is very small, but clearly composed of at least 

 three anchylosed segments. 

 Batliyurus? PI. I, fig. 8. 



A single specimen in the collection, or rather an impression of 

 one, from which I prepared a gutta-percha cast, leaves me in doubt 

 in regard to its generic affinities. 



The smooth, rather convex glabella, without indentation by 

 lateral furrows and the shape of the facial suture lines, resemble 

 some forms described by Billings under the name Batliyurus; 

 also the configuration of the other parts of the body would 

 agree with these, but the number of thoracic segments in the 

 specimen under observation is only six, while nine are claimed 

 for Batliyurm. Not considering the material on hand as suffi- 

 cient to decide whether this is a new generic type, or might be a 

 form of Bathyurus with a normal number of thoracic segments, 

 of which some became hidden by being shoved under the head, 

 I content myself for the present by giving an exact copy of the 

 gutta-percha cast formed in the impression of the slate-rock. 



AgnOStUS. PI. I, fig. g. Compare A. integer Barr. 



Many of these minute crustaceans are found scattered on the 

 slabs of slate. They all apparently belong to one species. 



The anterior valve differs from the posterior by the conical 

 shape of its glabella terminating near the front margin in a 

 bluntly pointed end ; the median line of this glabella rises near 

 the posterior end into a root-like crest, terminating in a back- 

 Avard j^rojecting spinose protuberance; the posterior part of the 

 glabella exhibits also an indentation by lateral furrows. 



The rachis or central convex protuberance of the posterior 

 valves is equilateral and not conical ; the posterior end of it it 

 a,bruptly rounded off; a deep furrow runs across this central 

 protuberance on the posterior third of it ; its larger anterior 

 portion bears a short spinose projection. 



The two thoracic annuli are divided by furrows and constric- 

 tions into nodular partitions representing rachis and ribs, but of 

 too small a size to be accurately represented by a descrijition, 

 or by figures. The subjoined figure of one of the specimens is 

 enlarged three diameters. 



Besides the described crustaceans, the slates inclose also num- 

 erous minute Brachiopods, several of which belong to the genus 

 OholeUa. One of these Obolellas, almost circular in outline, with 



