1904.] 



OSTEOLOGY OF CLUPEOID FISHES. 



475 



the suborbital plate, and they form a triangle with the posterior 

 half of the maxilla when the mouth is widely opened. 



Mandibular Series (text-figs. 134 and 135 A). — The mandible is 

 long, and the dentary bears teeth along the whole of its upper 

 edge. The coronoid process is situated far back, and does not 

 rise high in proportion to the length of the ramus. The angular 

 is not distinct from the articular, and there is no sesamoid 

 articular. 



Text-fiff. 135. 



Engraulis enorasicliolus. — A, hyopalatine arch and mandible of left side, mesial 

 aspect ; B, fourtli and fifth brancliial arches of left side, mesial aspect ; 

 C, hyoid of right side, with branchiostegal rays and subopercular bone, external 

 view. For explanation of lettering see p. 493. 



Hyopalatine Series (text-fig. 135 A). — The most striking features 

 of the hyopalatine arch are related to the backward tlii'ust of the 

 quadrate articulation. The axis of the quadi-ate slopes backwaixl ; 

 the axis of the hyomandibular also slopes backward, but the 

 symplectic is not in the same line with it, as might have been 

 expected. The hyomandibular articulates with the cranium by 

 two distinct heads, and the opercular head is faiidy long. The 

 edges of the palatine and ectopterygoid bear microscopic teeth, 



