100 Contributions to Palaeontology. 



quently subdivided ; divisions serrate or celluliferous ; 

 cellules numerous, little elevated above the axis, and 

 not mucronate. 



The following figures, already given in the Geological Report on 

 Wisconsin, illustrate the species, so far as the specimens in my 

 possession serve to furnish character. 



Dendrogeaptus hallianus (Prout.) 



a. A portion of the frond of the natural size. 



b. An enlargement of one of the branchlets, showing the cellules 



c. The main stipe and some of the principal branches, natural size. There 



is a swelling or protuberance at the base, or radicle, one side of 

 which is broken off. 



This species occurs in beds somewhat above the middle of the 

 formation, at Osceola mills on the St. Croix river. 



BR ACHIOP OD A. 

 GENUS LINGULA 1 (Bruguiere). 



^he Genus Lingula has been recognized in the lower rocks, from its 

 similarity of external form and texture to the recent Lingula. It may be 

 doubtful whether the internal structure and arrangement of muscular im- 

 pressions has been determined in any one of these, and it will probably be 

 a long time before this will be done for any large number of the species. 



