﻿ix. d. i Day: Ophiocephalus striatus 39 



The 26th rib (111) of the trunk is shown in Plate XII, fig. 2. 

 The 39th rib of the trunk (112), a single rib, is illustrated 

 in Plate XII, fig. 2. 



The 40th rib (113) is shown in Plate XII, fig. 2. 

 The 41st rib (114) is represented in Plate XII, fig. 2. 



VI. HYOID APPARATUS 

 PLATE XIII 



Plate XIII shows the hyals from the outside, except the 

 urohyal (68), which is seen from the ventral side. On the 

 left side of the plate the hypohyal (84), the ceratohyal (19) , and 

 the epihyal (20) are shown articulated, while on the right side 

 they are shown disarticulated. 



The ceratohyal (19) is shown in the natural size, the anterior 

 end being 4.5 millimeters in thickness and the posterior end 3 

 millimeters. Along the exteroventral margin is a fossa for the 

 articulation of the branchiostegals (22) . 



The flange on the ceratohyal is seen not to be continuous with 

 that of the epihyal (20). The first and second branchiostegals 

 (22) are articulated with the ceratohyal, and the end of the 

 third is opposite the V-shaped opening on the ventral side 

 between the pterygoid (80) on the outside and the urohyal (68) 

 on the inside. The ends are much splintered, especially the 

 posterior end. These are also seen from the dorsal side in 

 Plate XV. 



The outline of the epihyals (20) is clearly seen in Plate XIII. 

 The ventral side has a wide flange similar to that on the cera- 

 tohyals (19) for the articulation of the branchiostegals (22). 

 The posterior end has a condyle 4 millimeters thick. The 

 anterior end is splintered with a very large process or "splinter" 

 on the ventral side, which fits into a fossa in the posterior end 

 of the ceratohyal (19). 



The end of the third branchiostegal ray overlies the V-shaped 

 interruption between the ceratohyals (19) and the epihyals on 

 the ventral side, and the 4th and 5th rays articulate with the 

 flange of the epihyals. Dorsally, at the extreme posterior end, 

 the epihyals articulate with the ventral end of the interhyals 

 (21). The epihyals lie opposite the posterior end of the quad- 

 rates (7), the ventral end of the preopercles (11), and the 

 dorsal anterior portion of the interopercles (40). The dorsal 

 portion of the extreme posterior end lies at the side of the 



