green: ENCHODUS in KANSAS MUSEUM. 93 



tion of the chalk from the opposite side of the specimen, is in 

 position relative to the left pterygoid (pf) . The position of 

 the left metapterygoid, underneath the right pterygoid and 

 caudal end of the left dentary, is indicated by the broken line 

 which encloses an area in the figure the same shape and size 

 as the right metapterygoid (mt) . The mesopterygoid is also 

 in position relative to the metapterygoid and pterygoid. The 

 articular is characterized by definite rows of small tubercles 

 radiating from the cotylus. The shape of the preopercular is 

 shown in plate X, figure 1, pop. No radiating ridges are to 

 be seen on the expanded portion of this bone in any of the 

 specimens, but they were probably present, as so many of the 

 other bones display this character. This element is poorly 

 shown in the cotype. The left ceratohyal (ch) is fragmentary, 

 displaying no definite character. A portion of the right cera- 

 tohyal (ch) is present. It lies just to the right of the oper- 

 cular in the figure. The epihyal is attached to- the caudal end 

 of it, and lies beneath the right metapterygoid. The broken 

 line across the lower part of the right metapterygoid indicates 

 the outline of the dorso-caudal edge of this element. (Cf. 

 pi. XIII, fig. 1, eh; pi. XIII, fig. 3, ch; and pi. XI, fig. 2, eh.) 

 The opercular is strongly marked externally with radiating 

 tuberculated ridges. None of the specimens of this species 

 shows an external view of an opercular, but the specimen rep- 

 resented in plate X, figure 1, shows the impression of the ex- 

 ternal surface of both the opercular and the subopercular, in 

 the matrix. This indicates that they were both decorated with 

 distinct rows of tubercles radiating from the points of sus- 

 pension. The ventral margin of the opercular is concave, the 

 curvature being quite regular. This margin is present in both 

 figure 1 and figure 3. The mesial surface is smooth, except 

 for the stout bar which is present in all of the species. The 

 opercular is in position relative to the subopercular in fig- 

 ure 1. The interopercular is also decorated with numerous 

 tubercles, but they are very irregularly arranged. The sus- 

 pensory pharyngeal (s) is lying across a preopercular just to 

 the right of the metapterygoid in the figure of the cotype. 

 This bone is equal in length to the width of the ethmoid just 

 caudal the cephalic processes. The larger end has nearly twice 

 the diameter of the smaller, and the middle is slightly con- 



l-Univ. Sci. Bull.. Vol. VH, No. 2. 



