.MARYLAND GEOLOGICAL SURVEY 373 



described. The discovery of well-preserved examples of similar phyllo- 

 pods in considerable numbers in the lower part of the Martinsburg shale 

 just above the Sinuites zone is of considerable interest. These Middle 

 Ordovician phyllopods all conform to a single type for which the name 

 Caryocaris silicula is proposed. The species differs from the others of the 

 genus in its narrower or more elongated carapace, and a more nearly 

 equal anterior and posterior extremity. The latter characteristic is so 

 marked that it is difficult to discriminate the two extremities. 



A complete carapace is about 11 mm. long and 3.5 mm. high. No other 

 portions of the organism than the carapace have been noted. 



Occurrence. MARTINSBURG SHALE (Corynoides bed). Strasburg, 

 Virginia, and in the same zone northward to Chambersburg, Pennsyl- 

 vania. 

 I 



Collections. Maryland Geological Survey, IT. S. National Museum. 



