PLATE 73. 



MYLIOBATIDAE. 



Fig. 1. Myliobatis aquila. M. C. Z. 623 (Page 431). Fig. 2. Myliobatis peruvianus. 

 M. C. Z. 636 (Page 430). Fig. 3. Aetomylaeus maculatus. M. C. Z. 106 (Page 435). Fig. 4. 

 Aetobatus narinari. M. C. Z. 677 (Page 441). 



Three of the genera of the Myhobatidae are figured here. The fourth, Pteromylaeus, stands be- 

 tween Aetomylaeus and Aetobatus; it has the narrowed head and the separation of the pectorals as in 

 the latter, but has a different dentition. Myliobatis, fig. 1, differs from the rest of the family in pos- 

 sessing a continuous pectoral along the side of the head, and in absence of the modification of the pectoral 

 rays opposite the lower jaw. In all the genera the propterygial segment of the base of the pectoral 

 extends beyond the antorbital, that is beyond the head. In the very young this section of the base 

 appears to be somewhat irregularly segmented, but these indications are transitory, probably ancestral 

 tokens. The branchial ray at the outer end of the ceratobranchial is slightly modified at its point of 

 attachment to the pectoral base. The extra series of cartilages, evs, in front of the branchial rays along 

 the ceratobranchials and epibranchials are more developed than in preceding families. The extrabran- 

 chials, sbr, above and below, are well developed; they are modified branchial rays. The opercular 

 cartilages, op 1-5, are fringed. Extra cartilages, evs, appear upon or along the bands of the gill lamellae; 

 these may be called epitropeal, the upper ones being supratropeals, the lower subtropeals. 



