No. 2.] AMPHIUMA MEANS. 2)79 



pedestals for articulation with the axis. The exoccipitals join 

 each other only in a very small part of their length, being 

 separated by a V-shaped opening which is the foramen mag- 

 num. Immediately within this aperture, on either side, is 

 seen a small facet for articulating with the prezygapophyses of 

 the axis. The large foramina seen at the external sides of the 

 bases of the pedestals give passage to the vagus and hypoglossal 

 nerves. The exoccipitals are in apposition laterally with the 

 squamosals and stapes. They do not reach the prootics, which 

 lie anterior to the squamosals and external to the parletals, with 

 which they join in such a manner as to form the anterior parts 

 of the temporal crests. 



The pterygoids are wing-like bones extending from the 

 quadrates forward along the parasphenoid to near where the 

 vomero-palatines arise, at which point the bone gives way to 

 cartilage. The parasphenoid is the broad basal bone of the 

 skull, extending throughout more than half its length. It is 

 broadest in the otic region, and narrows in either direction. 

 Its posterior part is bounded on three sides by the exoccipitals. 

 Anteriorly, it extends beneath the ventral wedge of the pre- 

 maxillary. The stapes is an orbicular bone, scarcely three 

 millimetres in diameter, articulating with the parasphenoid, the 

 exoccipital, and quadrate. It does not form a part of the sus- 

 pensorium. The quadrate is a comparatively small bone, lying 

 on the inner side of the descending squamosal, and joins the 

 pterygoid, stapes, and parasphenoid. This bone, with the 

 squamosal, forms the suspensory apparatus. It bears the facet 

 for articulation with the mandible. The squamosal is another 

 peculiar bone in the Amphiuma skull. Wheiras in most of the 

 Urodeles it is directed forivards and slightly otit wards, in Am- 

 phitinia it is directed outwards and dowjiwards, and bnt very 

 slightly forwards. It is an exceedingly strong bone, and is 

 firmly adherent to the exoccipitals, parietal, and prootic above, 

 and joins the quadrate and stapes beneath. The possession of 

 this bone, according to Cope (4), allies the families Amphiu- 

 midae and Coecilidae. The bone which Cope has called squa- 

 mosal in the Coecilians is quite differently located, being 

 directed forwards and inwards in such a manner as to form 



