SEA-UUCIIINS. 



47P> 



from its iissooi:ites in point of size. Each tubercle in this median 

 series is phxce.l shohtly nearer the adoral than the adapical 

 transverse iiiari-in of the plate. All the otlier tubercles, of which 



Text-fiij. 58. 



'^J 



'©< 



'^,-. 



:©: 





B 









D 







.■@" .©.'a) :@: ' 



> 



H 



K 



Diagram showing the third plate above the ambitus in A. Fygaster sens. str. • 

 B.Solectypus (hemisphcericus) ; CHolecti/pus (depressus) ; B. Discoidea ; 

 E. Gnleropi/gns ; F. Anorthopijgus ; G. Conuhis. Figs. H & K are side 

 views of primary tubercles in Fygaster and ConvJus respectively. 



great numbers may occur in the later genera, are developed in 

 recognizably vertical series. When their number becomes great, 

 a natural tendency to slight irregularity appears, but this is never 



