410 



MESOZOIC TIME. 



ferent views, in profile, of a species of Ceratites, one of the genera of 

 the Ammonite group; and 710 C a second species, reduced in size 

 one third. The partitions are not seen over the exterior of the shell, 

 and hence nothing of them is shown in Fig. 710 C. In 710 A, a few 



Fig. 710 A, B, C, D. 



B 



Ammonite Family. — Fig. 710 A, Ceratites Haidingeri ; B, same in profile ; C, Ceratites Whitneyi 

 D, same showing form of pockets. 



are represented, to exhibit their character. Each downward flexure 

 corresponds to a depression or pocket-like cavity ; and, as in other 

 species of Ceratites, these pockets are quite simple in form, and nu- 

 merous. Fig. 710 D represents two of the pockets of 710 C. Fig. 

 744, p. 426, represents a foreign Ceratites ; and Fig. 746, another of 

 the Ammonite group, in which the openings of the pockets around the 

 margin of the outer chamber of the shell are shown. The mantle of 

 the living Cephalopod (whose body filled the outer chamber) descended 

 into the pockets, and thus aided the animal in holding to its shell. 

 Fig. 845, p. 463, represents another species of the Ammonite group, 

 of later age, which has the pockets very complex, as seen in Fig. 8456. 

 showing the outline of several of them. 



Figs. 711-712. 



711ft 



Figs. 711, a, b, Estheria ovata ; 712, Palephemera mediseva ( XK)- 



Articulates were represented in eastern America by both Crusta- 

 ceans and Insects. The Crustacean remains are, with a single excep- 



