PLATE LVI. 

 Trematopoka (Orthopoka) sdbquaurata. J^ttl 



Page 177. r^^^ 



See Plate 55. 

 Fig. . 1. An enlargement, showing- the form and disposition of the cell apertures and the character of the 

 interapertural space. (X 18.) 



Hamilton group. Darien Centre, Genesee cmmty, iV. Y. 

 Fig. 6. An enlargement, showing the cell apertures more broadly oval, and more closely disposed than in 

 tig. 1. (X 18.) 



Hamilton group. Near Canandaigva Lake, N. Y. 



Trematopoka (Orthopora) hexagona. ^^k 



Page 178. 

 See Plate 55. 

 Fig. 2. An enlargement, showing the form and disposition of the cell apertures, and the angular inter- 

 apertural space. (X 18.) 



Hamilton group. Hlghteen-miU-creek, Erie comity, N. Y. 



Thematopora (Orthopora) carinata. 



Pago 17». 

 See Plate 55. 

 Pig. 3. An enlargement, showing the form and disposition of the cell apertures, the alternating nodes, 

 and the prominent longitudinal ridges. (X 18.) 



Hamilton group. West Williams, Ontario, Canada. 



Trematopora (Orthopora) ornata. 



Pago 181. 

 See Plate 55. 

 Fig. 4. An enlargement, showing the form and disposition of the cell apertures, and the character of the 

 intei-apertural sui-face. (X 18.) 



Hamilton group. Oetuseo, N. Y. 



Trematopoka (Orthopora) reticulata. 



Page 179. 

 See Plate 55. 

 Fig. B. An enlargement, showing the form and disposition of the cell apertui-es, and the angular, granu- 

 lose and nodoee interapertural space. (X 18.) 

 Hamilton group. Western New York. 



Acanthoclema sulcatum. 



Page 19-i. 

 See Plate 56. 

 Fig. 7. An enlargt'ment, showing the form and disposition of the cell apertures, and the prominent 

 angular ridgen separating the ranges of apertures. (X 18.) 



Hamilton group. Darien Centre, Qenesee county, N. Y. 



Trematopora (Orthopora ?) orbipoka. 



Page 1S8. 

 See Plate 55. 

 Fig. 8. An enlargement, showing the foi-m and disposition of the cell apertures ; on a portion of the figure 

 the jKjri.ftnmes ai-e obsolete, and the interajiertural space elevated and nodose ; on the other 

 portion the peristomes ai-e moderately strong, and the interapertural space is flat or slightly 

 concave. (X 18.) 



Hamilton group. Near Canandaigva Lake, N. Y. 



