PLATE 64. 



PRISTIOPHORIDAE and PRISTIDAE. 



Fig. 1. Pristiophorus japonicus (Page 24G). Fig. 2-3. Pristis microdon (Page 265). 



1. Dorsal view. M. C. Z. 1045. 



2. Dorsal view. M. C- Z. 302. 



3. Ventral view. M. C. Z. 302. 



A species of the Antacea is placed by the side of one of the Platosomia to give prominence to differ- 

 ences between the two groups, which appear especially, among others, in the jaws, the branchial skeleton, 

 the shoulder girdle and the pectoral fins. The girdle of the shark, fig. 1, is remotely attached to the 

 vertebrae in its scapulary extensions; it is considerably arched and the fins are placed rather behind its 

 transverse axis. In the ray, fig. 2, the girdle is firmly and superiorly attached to the vertebrae by means 

 of a scapular element and the fins are lateral and forward of the articulations as well as behind them. 

 The copula, hhij, is divided into sections, segmented, and distinct from the cartilages behind it; in the ray 

 it is unsegmented and is attached to the ceratohyals, diij (chy in Plate). Strong cartilages appear in the 

 gill covers of the ray, sp. The postbranchial stay, phs, has its greatest development in Pristis and, as 

 shown in the following plates, dwindles in approaching the rays of highest rank. 



