﻿ix, d, i Day: Ophiocephalus striatus 21 



the basisphenoid (83) and the parasphenoid (66). They also 

 articulate anteriorly with the nasals (16) and the prefrontals 

 (76), outwardly laterally with the sphenotics (39), and with 

 the ethmoid (81) anteriorly. Posteriorly they articulate with 

 the pterotics (38). Just posterior to the ventral processes of 

 the frontals, and lying close to them, the alisphenoids (122) 

 are found. The oblique ridge-like ventral process of the fron- 

 tals is continuous with the alisphenoids (122), and the some- 

 what flattened dorsal portion of the alisphenoids (122) lies 

 against the flat ventral side of the frontals, posterior to their 

 processes. In Plate II the frontals are seen from the dorsal 

 side in the articulated top of the skull. In Plate III, dis- 

 articulated, the right is seen from the ventral side and' the 

 left from the dorsal. In Plate IV, fig. 2, the right frontal 

 is seen from the right margin as also in Plate VI, fig. 1. In 

 Plate V, fig. 1, they are seen in the articulated skull, from the 

 ventral side. The left frontal is seen in Plate I. 



The parietals (37) are roughly pentagonal in form, being 

 almost flat — slightly convex above — and very thin. They artic- 

 ulate with the frontals (36) anteriorly, the supraoccipital (35) 

 inside, the pterotics (38) outside, the epiotics (79) posteriorly, 

 and form a part of the roof of the accessory branchial chamber. 

 In Plate II the parietals are seen in the articulated skull from 

 the dorsal side. In Plate III they are disarticulated, the right 

 being seen from the ventral side and the left from the dorsal. 



The pterotics (38) are somewhat rectangular in form, but 

 with a spine-like process on the posteroexternodorsal side. The 

 lower side has a ridge in the form of an arc, which bounds the 

 portion serving as a part of the roof of the accessory branchial 

 chamber. They articulate with the sphenotics (39) anteriorly, 

 the parietals (37) inside, the epiotics (79) internally, and with 

 the head of the hyomandibulars (10) below. The interno- 

 posteroventral portion of the pterotics articulates with the 

 externoanterior portion of the opisthotics (123). The pterotics 

 are seen in Plate II from the dorsal side in the articulated 

 skull. In Plate III they are disarticulated, the right being 

 shown from the ventral side and the left from the dorsal side. 

 The left is seen in Plate I. In Plate VI, fig. 1, the right pterotic 

 is seen from the right side. In Plate V, fig. 1, the pterotics are 

 seen from the ventral side in the articulated skull. 



The sphenotics (39) are somewhat triangular and flat above, 

 with a ridge below, slanting inward, which unites with the 

 prootics (78). Internally and anteriorly the articulation is with 



