105 



CRUSTACEA. 

 No. 428. Lichas BoltOIli, Green. 



This beautiful Trilobite, rarely found entire, 

 is easily recognized by its peculiar scabrous sur- 

 face, depressed body and head, and the free ex. 

 trernities of the segments pointing backwards. It 

 is from the Niagara Group (Upper Silurian), Lock- 

 port, N. Y. Size, 7x6. Price, $1.50. 



No. 429. Lichas ( Tetraspis ) grandis, Hall. 



Head Portion. This is a most remarkable Trilobite form, by reason of the 

 deep furrows, tuberculated surface, and high, elongated nodes which diversify and 

 give a moustrous appearance to the cephalic buckler. From the Schoharie grit 

 (Devonian), Schoharie Co., N. Y. Original in the Ward Museum of the Univer- 

 sity of Rochester. Size, 7x6. Price, $1.75. 



No. 430. Lichas ( Tetraspis ) grandis, Hall. 



Pygiditjjvi. This specimen shows the reversed aspect of the caudal shield 

 with the strong ribs which sustain it, and long projecting spines. From the same 

 locality and the same Museum as the above. Size, 6x6. Price, $1.50. 



No. 431. Lichas pustulosus, Hall. 



Pygidium ; from the Lower Helderberg 

 (Lower Silurian), Schoharie Co. N. Y. 



Price, $0.60. 



No. 432. Lichas Trentonensis, Conrad. 



From the Hudson River Group (Lower Silurian), Cincinnati, O. Price, $0.30. 



No. 433. Ogygia Buchii, Goidf. 



This genus of trilobed crustaceans, so named in allu- 

 sion to their being found in the earliest fossiliferous for- 

 mation, is distinguished by a flat, semi-circular cephalic 

 shield, a very distinct facial suture, eight body segments 

 with free extremities, and a many-jointed caudal shield 

 with an axis as long as the body. It belongs to the Asa- 

 phida. This specimen is from the Llandeilo Flags (Low- 

 er Silurian), South Wales. Pripe, $0.60. 



