Proto. 



778 



cular on the external face ; rostral plate short and broad, etc.y 

 etc.; external surfaces marked with rounded ridges, 12 on car- 

 ina, 8 on rostrum, 6 on each carino-lateral, 4 on each rostro- 

 lateral, 3 on each lateral ; 7 operculaplates in three pairs, etc. 

 In the figure, part of the fringe is covered by an attached shell 

 {Leiorhynchus limitaris). Found at Avon, N. Y. in Marcellus 

 shale, VIII h. 

 Protoblechnum holdeni. (Alethopteris holdeni^ Andrews) 



