750 B. W. KUNKEL 



the maxillare it exhibits a processus palatinus and a processus 

 alveolaris. The former is horizontal, exhibiting a dorsal and a 

 ventral surface, and is prolonged anteriorly at its median mar- 

 gin to form a short process which extends nearly as far as the 

 anterior margin of the solum nasi and which may represent a 

 very rudimentary processus praenasalis. Even in the adult * 

 Emys, however, the praemaxillare remains wholly ventral to the 

 olfactory capsule and does not extend anterior to it to separate 

 the two fenestrae narinae from each other as in Lacerta, for 

 example. The processus alveolaris is a vertical plate extending 

 from the ventral surface of the processus palatinus in an oblique 

 direction from posterolateral to antero-medial. 



The postfrontale (pst.) has the form of a triangular plate with 

 an apex directed forward and its upper margin horizontal; its 

 antero-ventral margin is slightly concave and thickened by 

 a laterally projecting flange which arises near the ventral angle 

 of the bone and extends to the anterior apex. It lies in the space 

 between the quadratum posteriorly and the orbit anteriorly, 

 lateral to the parietale. It approaches the posterior extremity 

 of the zygomaticum with its ventrally projecting angle, and the 

 anterior margin of the quadratum in its most lateral portion with 

 its posterior margin. It has no share whatever in the formation 

 of the cranial wall. 



The parietale (par.) and frontale (/.) have essentially the 

 same relations to the chondrocranium that they do in Lacerta; 

 that is, tKeir position is wholly lateral and in the stage of Emys 

 modelled they do not begin to roof in the cranial cavity. The 

 parietale is large and triangular in form exhibiting long dorsal 

 and antero-ventral margins, a short posterior one, and a lateral 

 and a medial face. Its postero-dorsal angle is prolonged shghtly 

 to form a small processus occipitalis, extending dorsal to the otic 

 capsule for a short distance. Ventrally the paYietale is pro- 

 longed to form a processus inferior which extends downward 

 lateral to the pila prootica to come into close relationship with 

 the free end of the processus ascendens of the palatoquadratum. 

 The processus inferior thus comes to enclose a space external 

 to the primordial cranial cavity so that the latter is increased in 

 size on the sides. This space is the cavum epiptericum. 



