80 Edwin Cliapin Starks. 



C. Ethmoid concave in front. Nasals broad and attaclied for their 

 full length to frontals and ethmoid. Myodome opening directly 

 to exterior through a longitudinal foramen. 

 D. Temporal crests reaching straight forward to near front of 

 cranium. Caudal keel composed of membrane only.* The 

 last two or three vertebrai normal in size.^ 

 E. Supraoccipital crest reaching to ethmoid ; the full length 

 of cranium concave on each side of it. Preorbital part 

 of cranium not produced. The opening between ali- 

 sphenoids to brain chamber wide. The vertebrje num- 

 ber 49. ScoMBf3joMORiN.E. Scomberomorus. 



EE. Supraoccipital crest ending at front of eyes, anterior 

 to which the broad preorbital part of cranium is 

 transversely and evenly rounded and noticeably 

 lengthened. The alisphenoids nearly divide the 

 anterior opening to the brain case into two parts. 

 The vertebrne number G6. 



AcANTHOcYBiN^. Acauthocybium. 



D-D. Temporal crests slanting obliquely to supraoi'bital rim. 

 Caudal with a wide bony keel. The last two or three 

 vertebriB abruptly decreased in length. All of which 

 characters as in the ThunniniB, differing only as in divi- 

 sion "A." Sardine. Sarda. 



AA. Pterotic excluded from the brain chamber by a deep pit or infolding of 

 the bone behind prootic. Caudal peduncle with a bony lateral keel. 



CC. Ethmoid produced to a medium angle in front ; the nasals 

 slender and much projecting beyond it. Myodome opening to 

 a more or less specialized chamber in the parasphenoid. 



Thunnin^. 



1. Inferior vertebral processes normal. Thunnus. 



2. Haemal arches enormously developed and close to the centra. 



Euthynnus. 



3. Haemal arches not enlarged but carried far away from the 



centra by a long bony pedicle. Auxis. 



If we could eliminate the genus Scomber the family W'Ould be 

 much more compact, as it stands farther from the other genera than 

 they do from each other. The characters of Scomber may be for 

 convenience here summed ujj a little more fully than in the fore- 

 going key. It differs from all of the others in having the superior 



*I am indebted to Mr. Barton A. Bean of the National Museum for inves- 

 tigating the condition of the caudal keel in Acanthocybium. 

 ^This character has not been verified in Acanthocybium. 



