﻿ix, d, i Day:. Ophiocephalus striatus 25 



the vomer (67). Anteriorly are 4 cartilaginous projections, 

 2 in front and 1 at each side, and posteriorly 1 cartilag- 

 inous projection, which aid in articulation. These projections 

 are shown in the illustration. Ventrally the ethmoid is a much 

 narrower oval, and the thin median ventral portion overlies the 

 median parasphenoid (66) anteriorly. The whole bone is very 

 porous, especially the laterodorsal portions. It is visible from 

 the dorsal side, articulated, in Plate II, and disarticulated in 

 Plate III. 



The basisphenoid (83) has rather thick lateral wing-like pro- 

 cesses, which are slightly wider anteriorly than posteriorly, and 

 there is a short spinous portion posteriorly that fits into a longi- 

 tudinal slit-like fossa in the dorsal side of the parasphenoid (66). 

 The lateral portions articulate with the ventral ridges of the 

 frontals (36) and the alisphenoid (122) and slightly with the 

 anterior portions of the prootics (78). Plate III shows it from 

 the dorsal side; Plate IV, fig. 2, shows the anterior process of 

 the right side; and Plate V, fig. 1, the anterior process of the 

 left side — that of the right side not being visible here. 



The alisphenoids (122) articulate with the frontals (36), 

 laterally and dorsally, interoventrally with the basisphenoid 

 (83), posteroventrally with the prootics (78), and laterally 

 with the sphenotics (39). They lie close against the ventral 

 side of the frontals, and closely posterior to their ventral process. 

 On the dorsal side there is a flange supporting them against the 

 ventral side of the frontals (36). They are porous and some- 

 what perforated with sensory canals. They are shown in posi- 

 tion in Plate V, fig. 1, from the ventral side, while in Plate III 

 that of the right side is shown from the ventral side, disarti- 

 culated, with the outer margin toward the inside of the plate. 



The opisthotics (123) articulate with the exoccipitals (72) 

 and pterotics (38), overlying the space between the two bones 

 named and covering the epiotics (79) on the ventral side. 

 They are seen in Plate IV, fig. 1, the right being shown from the 

 dorsal side, while the left is shown from the ventral side. In 

 Plate V, fig. 1, both are seen from the ventral side in position, 

 and in Plate V, fig. 2, the view is from the posterior. In Plate 

 VI, fig. 1, the right is seen from the right side. They are 

 somewhat triangular, porous, and perforated by sensory canals. 

 These, together with parts of the epiotics (79), inclose a small 

 cavity in the ventral side of the latter. 



Suborbitals and preorbitals, 18 1 ~ 6 . The suborbitals are 18 5 , 

 18*, 18 3 , 18 2 , and 18 1 ; and 18 6 is the preorbital. These are all 



