﻿ix. d. i Day: Ophiocephalus striatus 41 



the median line and the seeming posterior portion indicate the 

 presence of a dorsal lamellar flange at right angles to the part 

 shown. The anterior view shows the urohyal to be somewhat 

 like an inverted T seen in text fig. 4. Anteriorly, both the 

 horizontal and vertical lamellae are thickened, so that the anterior 

 end is of the shape shown in the figure. It articulates by the 

 anteroventral fossa with the ventral side of the second basi- 

 branchial (17). Laterally and anteriorly it lies between, and 

 articulates with, the hypohyals (84) and continues posteriorly 

 between the ceratohyals (19) and the branchiostegals (22). 

 (Plates VI and XIII.) 



The hypohyals (84) articulate with each other just anterior 

 to the urohyal (68) and with the anterior portion, both hori- 

 zontal and vertical, of the urohyal. Poste- 

 riorly they articulate with the ceratohyals 

 (19) . Dorsally they articulate with the first 1^ 



basibranchial (17) and also with the ventral (pllli 



vertical ridge of the same. On the left side 11111 68 



the hypohyal is still articulated with the l|jis||l 



ceratohyal (19), while on the right side the ^^^''j^^zj 

 right hypohyal is disarticulated. These are ^s£L=o__i^^ 

 seen from the outer side. In Plate XV the interior rfew* x's. 8 *' 

 posterodorsal condyles articulate with the 

 second basibranchial (17) internally. The hypohyals are per- 

 forated with sensory canals. These are illustrated in Plate VI, 

 fig. 1, and Plates XIII and XV. 



VII. DORSAL RAYS AND INTERNEURAL SPINES AND ANAL RAYS 

 AND INTERHSEMAL SPINES 



The interneural spines and the interhsemal spines articulate 

 with the dorsal rays and anal rays, respectively, by ball-and- 

 socket joints. Between the two lateral parts of the rays at the 

 proximal ends are situated small spherical bodies (cartilaginous 

 nodules) which fit into the sockets at the distal ends of the 

 spines. In Plate XIV one of those posteriorly in the anal fin 

 is seen disarticulated and others in both fins are plainly visible. 

 Certain of the rays in both dorsal and anal fins present the 

 posterior view, which shows the two lateral parts of the rays, 

 their partial separation at the proximal end, and the cartilag- 

 inous nodules lying between their proximal ends. 



All of both the interneural and interhsemal spines are repre- 

 sented from the left side, the left side of the plate being anterior. 

 The posterior dorsal rays are not represented. 



