The O^lcitloiiv of llio S(,'(tiiil)ri(la\ 81 



crauial crests peculiar; the opistliotic, and the attaclmieiit of the 

 posttemporal to it normal ; the suborbital ring complete and carrying 

 a sensory tube ; the auxiliary maxillary very small ; the exoc- 

 cipitals not meeting above the basioccipital, and with their condyles 

 small and peculiarly placed, and in having neither a bony nor a 

 membranous caudal keel. 



Eastrelliger, Jordan and Starks, has departed but slightly from 

 Scomber, differing chiefly in the way in which the metapterygoid 

 assists the quadrate in supporting the pterygoid ; in the high knife- 

 like ridge formed by the basibranchials ; and in the great develop- 

 ment in the length of the gill-rakers. It is othermse as in 

 Scomber. 



Certain characters indicate that Scomberomorus has come more 

 directly from the Scombrina? than have any other of the genera here 

 considered, though its evident alliance with Acanthocybium — possibly 

 the most aberrant of its family — shows hoAV far it lias departed from 

 the Scomber type. Consequently the fact that Scomberomorus is here 

 most closely approximated to Scomber does not necessarily mean 

 that it is the most closelv related to that ffenus, but that its descent 

 is more directly traced. It has no bony caudal keel, but a mem- 

 branous one shows a development in the direction of one ; its cranial 

 crests are directed straight forward, though they are not interrupted 

 as in Scomber ; its auxiliary maxillary is small ; and its last two 

 or three vertebra? are normal, or not abruptly decreased in length. 



Acanthocybium naturally comes next to Scomberomorus, though 

 as is intimated above it certainly does not deserve a position so close 

 to Scomber. It shows, as was long ago pointed out, an apparent 

 divergence towards the sword fishes. 



The exact position of Sarda is a little obscure. It has the concave 

 ethmoid and non-projecting nasals of Scomberomorus and Acantho- 

 cybium, but has the cranial crests arranged almost identically as in 

 the Thunninse. On the lower surface of the cranium is a slight 

 depression showing a development towards the deep pit of the 

 Thunninse and the caudal peduncle has a lateral keel. Consequently 

 it must have sprung from somewhere betAveen the Scomberominse and 

 the Tliumiina3 to have such marked characters of both groups. It 



