172 



DR. A. SMITH WOODWARD ON 



[June 7, 



to be interpreted as a partially ossij&ed. basioccipital element 

 forming only an insignificant part of the occiput. The condyles 

 themseh^es (c.) are convex and seem to have been covered with 

 unossified cartilage, while they constitute the hindermost entl of 

 a pair of bones which enter extensively into the base of the 

 cranium and also rise upwards to bound the foramen magnum 

 on each side. These elements (ex.) therefore exhibit the same 

 disposition as the exoccipitals of a frog, and must be homologous 

 with the latter. They are pierced by the foramen for the vagus 

 nerve, which is well seen on the left side. The posterior face of 

 each exoccipital immediately above the condyle is impressed with 

 a triangular fossa, so that the upper end of the bone, partly 

 obscured by matrix, has the appearance of bifurcating to unite in 

 jagged sutures with the two bones which descend from the 

 occipital row of roofing plates. The latter plates are evidently 

 superficial in origin — either dermal or splint ossifications — but 

 there is no clear line of deiiiarcation between them and the 

 immediately underlying bones just mentioned. The inner half of 



.d. 



Text-fig. 34. 

 f)p ep. socc. sb. 



CapUosaurus stantonensis ; hinder view of occiput, restored, two-thirds nat. size. 



hocc, supposed basioccipital ; c, occipital condi'le on exoccipital; ep., epiotic ; 

 ex., exoccipital; fm., foramen magnum; op., opisthotic; psq., prosqimmosal ; 

 pt., pterygoid ; ptv., postero-temporal vacuity ; qj., quadrato-jugal; qu., quadrate ; 

 socc, space for supraoccipital ; st., supratemporals. 



each plate of the median pair would directly overlap t]\e carti- 

 laginous supraoccipital ; while its outer or lateral half alone is 

 underlaid by the bone (ep.) which occupies the place of a piscine 

 or amphibian epiotic. The inner two-thirds of each plate of the 

 outer pair is underlaid by the second bone {op.) of triangular 

 shape, which exhibits the usual relationships of an opisthotic. 

 As shown on the right side of the fossil, the jagged suture 

 between these two otic bones coincides exactly with that dividing 

 the two overlying plates. The pterygoids unite in a deeply jagged 

 suture with the bi-oad basioccipital region, and then expand behind 

 on each side into a vertical lamina (jOi5.) which articulates with 



