﻿24 The Philippine Journal of Science wu 



sory canal. In Plate II they are seen articulated from the dorsal 

 side; in Plate III from the dorsal, disarticulated; and in Plate 

 V, fig. 1, articulated, from the ventral side. In Plate IV, fig. 

 2, and Plate VI, fig. 1, the right is seen, articulated, from the 

 right side. In Plate I the left is dimly seen. 



In Plate V, fig. 1, the ventral side of the prootics (78) is 

 shown in position. In Plate III the left is shown from the 

 dorsal side, and the right from the ventral. In Plate IV, 

 fig. 2, and Plate VI, fig. 1, the right is seen laterally. They 

 articulate with the parasphenoid (66) ventrally and internally, 

 the sphenotics (39) laterally, the alisphenoids (122) latero- 

 dorsally, the basisphenoid (83) interodorsally, the exoccipitals 

 (72) posterodorsally, the basioccipital (69) posteriorly, and 

 contain within them the otoliths (73). The form is shown in 

 the illustrations. The myodome or chamber for the insertion 

 of the rectus muscle of the eye is formed by projecting shelves 

 of bone from the internal sides of the prootics, and is separated 

 from the brain cavity by them. The basioccipital (69) also 

 assists here. It is concave on the ventral side, forming a cavity 

 with the parasphenoid (66). This cavity opens to the exterior 

 by an opening on either side from above the posterior end 

 of the parasphenoid (66). 



The epiotics (79) articulate with the pterotics (38) on the out- 

 side, with the exoccipitals (72) on the inside, and internoante- 

 riorly with the supraoccipital (35) and parietals (37). The 

 main portion is somewhat pyramidal, with the base turned ante- 

 riorly and outwardly. Posteriorly and obliquely toward the spi- 

 nal column is a broad expanse of thin bone about the same length 

 as the main portion of the bone. This is somewhat fan-like with 

 concentric rings. This thin expanse stands at almost a right 

 angle to the body of the bone. As illustrated in Plate V, fig. 1, 

 they articulate with the opisthotics (123) which overlie the 

 posterolateral portion of the ventral surface of the epiotics. 

 They are seen in Plate II, articulated, from the dorsal side; in 

 Plate V, fig. 1, the posterior fan-like expanse from the ventral 

 side; and in Plate V, fig. 2, is the posterior view. In Plate IV, 

 fig. 1, the right is displayed from the dorsal side, while the left 

 has the ventral side uppermost. In Plate IV, fig. 2, the right 

 side of the posterior portion of the right bone is visible. 



The ethmoid (81) is somewhat oval above, with two lateral 

 processes dorsally which articulate with the nasals (16). Lat- 

 erally it articulates with the prefrontals (76). posteriorly with 

 the frontals (36). and ventrally with the parasphenoid (66) and 



