Tlie Osteology of the Scombridse. 



95 



EUTHYNNUS. 

 A specimen of Eutbynnus pelamis (Linnaeus), 19 inches in length, from 

 Japan. 



In this form the cranial crests, the condition of the ethmoid and 

 nasals, the chamber in the parasphenoid into which the myodome 

 opens are all nearly identical with these characters in Thunnns and 

 Anxis. It differs in having the alisphenoids separated, and the 

 vomer toothless. The large pit behind the prootic has nearly broken 

 through the top of the craninm where the bone is very thin and 



A 



B 



D 



Pv.-' 



•J f 



H 



Fig. 1. — VEBTEBR.E OF EUTHYNNUS. 



A. Front view of 15th abdominal vertebra. 



B. Lateral view of 11th and 12th abdominal vertebriB. 



C. Lateral view of 15th and IGth abdominal vertebrae. 



D. Lateral view of 3d and 4tb caudal vertebrae. 



E. Lateral view of 8th and 9th caudal vertebra?. 

 iz., inferior zygopophysis. 



if., inferior foramen. 



h. c hipmal canal. ^ 



p., parapopbysis. 



h., hremal arch. 



1'., rib. 



pierced by several small holes. On top of the craninm jnst behind 

 the frontal at each side of the snpraoccipital crest, where in Thunnns 

 is a large smooth opening to the brain cavity, the bone is irregularly 

 broken through ; the opening being much wider on one side of the 

 cranium than on the other in the specimen at hand. There is no 

 infolding of the bone between the prootic and alisphenoid, and there 



