10 PROCEEDINGS OF THE NATIONAL MUSEUM. 



InterliiBmals evenly graduated iu leugtli from behind forward, the 

 anterior one not differentiated. 



Yertebral formula : Abdominal, 13 ; caudal, 11, which, with the hypu- 

 ral, are 21. 



Atlas short, the succeeding vertebraj elongate and rather smooth, 

 without deep pits, and much constricted iu the middle. 



Anterior and posterior zygapopbyses well developed. 



Parapophyses not developed anterior to ninth vertebra. 



Evidence apparent of hypural having beeu developed from two pos- 

 terior vertebrae. 



Hypural assisted in bearing caudal flu by spines from two preceding 

 vertebrai and some detached auxiliary spines taking the place of neural 

 spine of first i^receding vertebra. 



Lateral i)rocesses from hypural large and flat, forming a keel. 



Last i:)air of ribs flrmly anchylosed with last pair of parapophyses. 



Epipleurals present. 



EXPLANATION OF PLATES. 



SIGNIFICANCK OP REFERENCE LETTERS USED ON PLATES. 

 [From drawings by Cliloe Lesley Staiks.J 



als. 



Alisplienoid. 



bo. 



Basioccipital. 



bs. 



Basisphenoid. 



epo. 



Epiotic. 



c. 



Ethmoid. 



eo. 



Exoccipital. 



.fr. 



Frontal. 



na. 



Nasal. 



opo. 



Opisthotic. 



pas. 



Parasjihenoid. 



P- 



Parietal. 



pro. 



Prootic. 



pto. 



Pterotic. 



Pf- 



Prefrontal. 



spo. 



Sphenotic. 



so. 



Supraoccipital 



V. 



Vomer. 



Plate L 





Superior views of the crania of Sphyricna argenieu, Atherinopsis calif ornienais, and 

 Mugil cephalus. 



Plate II. 



Lateral views of the crania of Spliyrwna argeiitea, Atherinopsis calif orniensis, and 

 Mugil cephalus. 



Plate III. 



Posterior views of the crania of Sphyrwuu argentea, Atherinopsis califoruiensis, and 

 Mugil cephalus. 



