The Osteology of tlie Scombridse. 85 



anteriorly; the short premaxillary processes scarcely reach to it. A . 

 basisphenoid is present and is separated from the roof of the myo- 

 dome as nsual ; it has a process descending to the parasphenoid. The 

 alisphenoids do not meet each other. 



A well developed preorbital is present and the suborbital ring is 

 complete, consisting of thin plates along the anterior edge of which 

 runs a small sensory tube. There is no suborbital shelf, and the eye 

 has a bony sclerotic case as do all the other members of the family. 

 The nasals are attaclied to the sides of the frontals and project far 

 forward beyond the ethmoid. 



The head of the hyomandibular, by which it is attached to the 

 cranium, is divided into two parts, a round knob in front and an 

 elongate portion behind, well separated from each other. The 

 metapterygoid is channeled on its posterior edge to receive the edge 

 of the hyomandibular, and behind the hyomandibular it sends a long 

 triangular process backward half way across the preopercle. It has a 

 large articular facet on its posterior edge to support the opercle. 

 The symplectic is long and slender, somewhat broadened behind the 

 metapterygoid, and extending behind the quadrate in a channel. The 

 opercle bones are wide and fit smoothly together without ridges ; the 

 preopercle in particular is broad. The wedge-shaped process of the 

 articular does not nearly fill the usual deep notch of the dentary, thus 

 leaving a considerable space between these two bones along the upper 

 edge. A well developed angidar is present. The premaxillary and 

 dentary teeth are small and set in alveoli. On the inner anterior 

 edire of the maxillary is a large -articular facet for attachment to the 

 side of the vomer. On the posterior upper edge is a small auxiliary 

 maxillary. The maxillaries are not in contact with each other 

 anteriorly. The premaxillary processes are heavy, short, and trian- 

 gular, and they do not project backward to reach the ethmoid. 



The hypohyals are very large and are paired on each side ; a wide 

 flat glossohyal is present ; the broad urohyal has scarcely any lateral 

 wings developed along its lower edge. Four branchiostegal rays are 

 attached to the ceratohyal and three to the epihyal ; the anterior ones 

 are attached to the lower edge of the arch, but they creep up to the 

 outer surface posteriorly. A short interhyal is present. 



