PLATE XXIV— Continued. 



PllAETHONIDES CYCLURUS. 



Page 137. 



See Plate 25. 



Fig. 26. A fragment of the cephalon, showing the lateral furrows of the glabella, a little too strongly. 



Enlarged to three diameters. 

 Fig. 26a. Outline profile of the same. 



Lower Helderberg group. Near ClarksviUt. Albany county. 

 Fig. 27. A pygidium, drawn from a gutta-percha impression of the internal surface The axial row of 

 tubercles should be represented a-s duplicate at the fifth annulation, as in fig. 28. Enlarged to 

 three diameters. 



Lower Helderberg group. Near Clarksvitte, Albany county. 

 Fig. 2S. Another pygidium retaining the crusf and showing the character of the dorsal surface. Enlarged 

 to three diameters. 



Lower Helderberg group. Near C larksville, Albany county. 



Phaethonides varicella. 



Page 135. 

 Fig. 29. The intra-sutural portion of a cephalon, showing the tubercled and punctate surface. Enlarged 



to three diameters. 

 Fig. 29a. Outline profile of the same, showing the depressed frontal area and elevated margin. 



Corniferous limestone. Canandaigua, Ontario county. 

 Fig. 30. An imperfect cephalon, drawn from a natural cast of the internal surface. Enlarged to three 



diameters. 

 Fig. 30a. Outline profile of the same. 



Corniferous limestone. Canandaigua, Ontario county. 

 Fig. 31. A pygidium, drawn from a natural cast of the internal surface. Enlarged to three diameters. 

 Corniferous limestone. Canandaigua, Ontario county. 



Phaethonides GEMM.EUS. 

 Page 136. 

 Fig. 32. A pygidium, showing the characteristic ornamentation. Enlarged to two diameters. 



Hamilton group. Canandaigua. Ontario county. 

 Fig. 33. Another pygidium. The axial node on the posterior margin is made too distinct in the drawing. 

 Enlarged to two diameters. 



Hamilton group. Eighteen-mile Creek, Erie county. 

 Fig. 34. A fragment, showing seven segments of the thorax. Enlarged to two diameters. 



Hamilton group. Canandaigua Lake. 

 Fig. 35. A pygidium, drawn from a gutta-percha impression of the internal surface which retains the 

 doublure, showing the strongly punctate character of the surface between the ribs. Enlarged 

 to three diameters. 



Corniferous limestone. Canandaigua, Ontario county. 

 Fig. 36. A small pygidium in which the marginal tubercles are unusually conspicuous and become spini- 

 form. Enlarged to two diameters. 



Corniferous limestone. Canandaigua, Ontario county. 



