88 ANATOMY OF VERTEBRATES. 



closing the homolosfue of the * fenestra ovalis.' The basi- 



o o 



sphenoidal portion of the basicranial plate sends out an angular 

 process on each side, which supports the alisphenoid. The 

 surfaces of the alisphenoid are directed forward and backward, 

 instead of from side to side, and it constitutes chiefly the anterior 

 parietes of the otocrane ; the inner and anterior border is 

 notched by the great trigeminal nerve. The parietals are long 

 and broad, divided by the sagittal suture, and impressed at the 

 posterior and outer angle by the anterior attachment of the great 

 dorsal trunk-muscles. The masto-tympanic is articulated to this 

 part of the parietal and to the exoccipital ; it includes all the 

 divisions of the pedicle save the lowest, ( hypotympanic,' which 

 affords the articulation to the mandible. The orbitosphenoids 

 are divided by an unossified tract of some extent from the ali- 

 sphenoids, and articulate above with the extremity of the parietal, 

 the frontal and prefrontal bones. There are neither paroccipitals 

 nor postfrontals. The vomerine portion of the basicranial plate 

 is chiefly cartilaginous. The turbinals are very small, and 

 separated from each other by the junction of the premaxillaries 

 with the frontals. The bone extending from the frontal to the 

 maxillary in front of the orbit may be termed ( antorbital ; ' the 

 ossification which extends therefrom, in higher Batrachians, takes 

 the situation of the facial plate of the prefrontal, of the nasal, and 

 of the lacrymal. The pedicles ( tf apophyse montante,' Cuvier,) 

 of the premaxillaries are long and narrow. The small maxillary is 

 attached to the antorbital, to the palatine, and to the premaxil- 

 lary ; the end of the bone extends freely backward as in the 

 Menopome, fig. 43, 21. The alveolar border of both premaxillaries 

 and maxillaries supports a single row of small equal and sharp- 

 pointed denticles. Two bones attached to the anterior and outer 

 part of the basicranial bone, and which may be regarded either as 

 ' vomerine or palatal, support each a narrow rasp-like group of 

 minute denticles, which are continued backAvard upon the be- 

 ginning of the pterygoids ; the pterygoids continued from these 

 bones and from the sides of the basicranial bone expand as they 

 extend backward and apply themselves to the inner side of the 

 tympanic pedicle. The nasal meatus has its posterior termination 

 between the beginning of the pterygoid and the end of the 

 maxillary bones. Besides the ordinary row of denticles upon the 

 clentary piece of the lower jaw, there is a second shorter series 

 upon the splenial piece. 



In theMeiiobranch(^/eft0Z/Ymc//s later alls) the occipital condyles 

 are transversely oblong, convex vertically, concave transversely, 



