﻿ix, d. i Day: Ophiocephalus striatus 23 



of the auditory capsule. The dorsal side borders the foramen 

 magnum. In Plate IV, fig. 1, it is seen from the dorsal side; 

 in Plate IV, fig. 2, from the right side, articulated; in Plate 

 V, fig. 1, in the articulated skull from the ventral side; and 

 in Plate V, fig. 2, in the articulated skull from the posterior. 



The exoccipitals (72) border the foramen magnum on the 

 dorsal and internal side. A short distance within the foramen 

 they unite as a narrow bridge of bone just dorsad to the 

 bassioccipital (69), which latter forms the ventral side of the 

 foramen at the posterior opening. The lateral portions extend 

 outward and upward, articulating with the epiotics (79) later- 

 ally, with the supraoccipital (35) anteriorly above, with the 

 prootics (78) anteriorly ventrally, and with the bassioccipital 

 (69) below. The median portion of the dorsolateral process 

 articulates with the ventral margin of the opisthotics (123). 

 The exoccipitals are seen from the dorsal side of the articulated 

 skull in Plate II; in Plate IV, fig. 1, disarticulated from other 

 bones, from the dorsal ; and in Plate V, fig. 2, in the articulated 

 skull from the posterior. In Plate IV, fig. 2, and Plate VI, 

 fig. 1, the right shows from the right side. 



Otoliths (73). In a fish 50 centimeters in length, these are 

 18 millimeters long, 10 millimeters wide, and 3 millimeters 

 thick. They are irregularly oval, somewhat curved, and on 

 the convex side is a somewhat S-shaped groove over the whole 

 length. In color they are like milky quartz, and there are 

 concentric lines running about them like the rings of growth 

 in the shell of the Pelecypoda. In Plate II the left, and in 

 Plate III the right, is seen from the side fitting against the 

 outer margin of the prootic (78), while in the same plates 

 the other is seen from the inside or concave surface. 



The supraethmoid (75) is a light, spongy bone, which in 

 very young forms is cartilaginous. It is thickest posteriorly. 

 The general form from the dorsal side can be seen very well 

 in Plates II and III. It is situated dorsad to the anterior por- 

 tion of the ethmoid (81) and the posterior portion of the head 

 of the vomer (67). It is partly ventrad and partly posterior 

 with respect to the dorsal processes of the premaxillaries (1). 

 The supraethmoid, together with the dorsal processes of the 

 premaxillaries, extend dorsally through the opening between 

 the curved sides of the nasals (16). 



Lying laterally to the ethmoid (81) and anteriorly to the 

 frontals (36) are the prefrontals (76), somewhat wing-like 

 laterally, and perforated anteriorly posteriorly by a large sen- 



