PLATE XXI. 



PAGE. 



Fig. 1. Ch^tetes Dalei 192 



1. Fragment. Natural size. 



la. Portion of the surface of the same. Enlarged. 



Chjetetes eugosus 193 



Frafipnent. Natural size. 



Ch.'etetes approximatus 193 



Fragment. Natural size. 

 3a. Portmn of the surface of the same. Enlarged. 



Ch^tetes attritus 194 



Fragjment. Natural size. 

 4a. Portion of the surface of the same. Enlarged. 



Ch^etetes pulchellus 195 



Fragment. Natural size. 



Portion of the surface of the same. Enlarged. 



CHiETETKS SUB-PULCHELLUS 196 



Frapnent. Natural size. 



Portion of the surface of the same. Enlarged. 



Fig. 7. Ch;etete8 Fletchbri 197 



7. Fragment. Natural size. 



la. Portion of the surface of the same. Enlarged. 



Fig. 8. Ch^tetes gracilis 198 



8. Fragment. Natural size. 



8a. Portion of the surface. Enlarged. 



86. Portion of the suri'ace. Still farther enlarged. 



Fig. 9. Ch-etete:s delicatulus 190 



9. Fragment. Natural size. 



9a. Portion of the surface of the same. Enlarged. 



Fig. 10. CH.ETETES NODULOSUS 200 



10. Fragment. Natural size. 



10a. Portion of the surface of the same. Enlarged. 



Fig. 11. CnjcTETES Jamesi 200 



11. A somewhat lobate spncimeu, showing the rounded ends of the bi'auch^'s. Natural size. 

 11a. Portion of the surface uf the same. Enlarged. 



Fig. 12. Ch^etetes rhombicus 201 



12. Fragment, showing the termination of a branch. Natural size. 

 12a. Pomon of tho surface of the same. Enlarged. 



Fig. 13. GlI.ETETES BRIAREUS 202 



13. An example, with four primary branches springing l!rom the basal cone. Natural i-ize. 

 13a. Another example, with only two primary branches arising from tho basal cone. Natural 



size. 

 136. Portion of the surface. Enlarged, 



Fig. 14. Gn^TETES petropolitanus 204 



14. A small example, apparently belonging to this species, growing upon the valve of a 



Sb'Ophomena. 

 14a. Portion of the surface of the same. Enlarged. 

 146. Side view of a vory small example of G. petropolitanus^ having the typical free mode of 



gi'owth, showing the great comparative height. Natural size. 



Fig. 15. ClI.ETETES DISCOIDEUS 206 



15. A specimen of the average size, viewed from above. Natiiral size. 

 15a. Concave under surface of the same. Natural size. 



1.56. Profile view dl the same, sliDwing the great comparative thinness of the disc. Natural 



size. 

 15c. Portion of tho surface of the same. Enlarged. 



