PLATE XXVIII. 



Cystiphyllum Americanum. 



CysUphyllum Americanum. Edwards - Haime. Polyp. Foss. Terr. Palaeozoiques, p. 464, pi. 13, flg. 4. 



cylindricum Hall. Geology of N. Y. Surv. Fourth Dist., p. 209, ligs. 1, 2. 1843. 

 Not " " Lousdale. 



Fig. 1. Lateral view of a medium sized specimen, from wliicli the epitheca has been eroded, ex- 

 posing the cysts over nearly the entire surface. Moscovi', New York. 



Fig. 2. A larger specimen, showing a similar condition, and having the cup contracted to about 

 half the size of the body below. Town of Bosanquet, Ontario. 



Fig. 3. Longitudinal section of a specimen, showing the cystose structure. Sl<aneateles Lake, New 

 York. 



Fig. 4. Lateral view of a twin corallum, the two cells being enclosed by a continuous epitheca. 

 The sudden contraction near the summit is caused by a twin budding of the same 

 character; and from the later divi.'ion on the right side a distinct and independent 

 bud had commenced its growth. 



Fig. 5. Lateral view of a specimen preserving the external epitheca, and exhibiting an unusual 

 degree of regularity in its mode of growth. 



Fig. G. View ol the interior of the cup of the preceding specimen, showing a slight tendency to 

 Ibrm rays along the surface of the cysts. 



Fig. 7. Transverse section of a specimen, showing the whole structure to be without rays or con- 

 centric rings. 



Cystiphyllum varians. 



{See Plate 29.) 

 Fig. 8. Transverse section, showing the cysts arranged in concentric circles, formmg cups as in 

 Chonophyllnm. and also showing that the incipient rays are developed into continuous 

 lines in the interior. 



