ring around the rear of the peduncle, and another set of 

 plates more anteriorly just behind the bases of the dorsal 

 and anal fins form broad saddles above and below the 

 peduncle which do not meet one another mediolaterally. 

 In Kentrocapros, Aracana, and Strophiurichthys the two 

 anterior saddles are similar to those of Capropygia and 

 Anoplocapros, except that the individual scales making 

 up the anterior saddle in Kentrocapros and Aracana are 

 less well-consolidated into a single unit than they are in 

 Strophiurichthys, Capropygia, and Anoplocapros. 

 Posteriorly, instead of a complete ring around the pedun- 

 cle as in Capropygia and Anoplocapros, there are similar 

 saddles over the dorsal and ventral regions of the pe- 

 duncle that fail to meet mediolaterally, although in large 

 specimens the edges of these two posterior saddles are al- 

 most in contact. In the Eocene Proaracana the dorsal and 



Figure 139.— Kentrocapros aculeatus: 



dorsal view of branchial arches 



(extended on lower side); lateral 



view of hyoid arch and urohyal; 



90.7 mm SL, Japan. 



lU^i 





1111=1 



scale plates on the caudal peduncle. These plates are 

 least developed in Caprichthys, in which there are only 

 one to three relatively small scutes dorsally and ventrally 

 on the anterior region of the caudal peduncle just behind 

 the bases of the dorsal and anal fins. The caudal plates 

 are best developed in Capropygia and Anoplocapros, in 

 which a posterior set of plates forms a completely closed 



ventral regions of the caudal peduncle are covered with 

 numerous semi-isolated small scale plates that do not 

 form compact saddles, and the mediolateral region is 

 scaleless. 



The center of each carapace scale plate in most spe- 

 cies usually bears a spinule larger than those of the rest of 

 the plate, while large prominent spiny processes are vari- 

 ously developed. In Kentrocapros there is a small 

 supraorbital spine, a larger one on the dorsolateral ridge 

 and several on the mediolateral and ventrolateral ridges. 

 Aracana is similar to Kentrocapros, but with the 

 supraorbital spine larger and with two or more spines on 

 the dorsolateral ridge. In Capropygia and Caprichthys 

 there is a single large spine on the dorsolateral and ven- 

 trolateral ridges, with Caprichthys additionally having a 

 small supraorbital spine in the young which is resorbed 

 in the adult. In Anoplocapros and Strophiurichthys 

 prominent spines of the magnitude found in the other 

 genera are absent, although in large adults of one of the 

 species of the latter genus, S. robustus, there is a small 

 supraoccipital spine and the central spinule of many of 

 the individual scale plates of the carapace is relatively 

 much larger than the others, forming spines interme- 

 diate in size between those on the ridges of such genera as 

 Kentrocapros, Aracana, Capropygia, and Caprichthys, 

 and those of the center of the plates in all other species. 

 Young specimens of all species probably have the 



