EXPLANATIONS OF PLATE* 12 « (I). 



GrOMPHOCYSTITES TENAX. page 310 (6). 



Fi^. 1. Lateral view of the upper part of the body, showing tlie arrangement ofplates. 

 the spiral grooves indicating the places of the sessile arms are at the upper 

 margins of the ranges of smaller plates. 



The plates are more or less irregularly disposed in some parts of the 

 body; but they appear, like others of the genus, to have a generally spiral 

 arrangement. (Enlarged to two diameters). 

 " 2. The summit, showing the arrangement of the spiral arms, and the central aperture. 

 The diagi-am is made from an imperfect specimen, and the position of the 

 excentric aperture could not be ascertained. 



GoMPHOCYSTiTES CLAvus. page 310 (6). 



Fig. 3. A fragment (natural size) showing the disposition of the spiral arms and the 

 obtusely angular form of the body below. 



GoMPHOCYSTiTES GLANs. page 310 (6). 



Fig. 4. Lateral view of a specimen showing the entire form, and the disposition of the 

 spiral arms. 

 " 5. The anterior ? view of another individual of the same species. 



HOLOCYSTITES ALTERNATUS. page 312 (8). 



Fig. 6. A posterior ? view of a specimen (natural size) showing the position of the 

 excentric aperture, form and relation of plates, etc. 



HoLocYSTiTES CYLiNDRicus. page 311 (7). 



Fig. 7. View of a nearly entire individual, showing the central aperture in a depression 

 at the summit. The plates of the lower part are broken off. 

 " 8. A smaller individual, in which the plates have been strongly ridged : preserving 

 a portion of the column. The lower ranges of plates are somewhat obscure, 

 and the dotted lines indicate depressions which may be sutures or only 

 grooves in the larger plates. 



Apiocystites imago. page 314 (10). 



Fig. 9. Lateral view of specimen showing the ovarian aperture on the left hand side of 

 figure, and the right pectinated rhomb (Figure natural size). 



Crinocystites chrysalis. page 318 (14). 



Fig. 10. View of the gibbous side of the specimen. 

 " 11. A lateral view of the same specimen. 



♦This plate accompanied the original paper as Plate I. It is now arranged with the 

 other plates in its order as 12 a (I). 



