PALATO QUA URATE WITH NEUROCRANIUM IN OCELACANTHIDS. 49 



process to the adductor muscles of the mandible are thus not the 

 same as in fishes, but this is probably not important, for the 

 superior and inferior branches of the nervus trigeminus both run 

 forward dorsal or mesial to the process and then turn outward 

 anterior to it. The process lies between the pars articularis 

 quadrati and the processus basalis, in the same relation to those 

 two processes that the processus metapterygoideus of fishes has, 

 and hence is quite certainly the homologue of the latter process. 

 In the Apoda there is said to be no processus basalis (Gaupp, 

 1905, p. 753). 



In the Stegocephali, the palatoquadrate is said to be movable 

 in certain forms, but fixed in by far the larger number. In 

 Eryops there is, according to Yon Huene (1912), a basipterygoid 

 process which is apparently a definite process of the basisphenoid 

 bone, but as there is no suture separating the basisphenoid and 

 parasphenoid, the latter bone may also enter into the process. 

 The pterygoid is said to be attached (befestigt sich) to the process 

 by a broad articular surface, the palatoquadrate thus apparently 

 being movable. In Archegosaiorns, the parasphenoid has, according 

 to Watson (1919), a narrow, outstanding basipterygoid process 

 on either side, and the pterygoid articulates with it by a freely 

 movable joint ; and similar basipterygoid processes are apparently 

 found in several others of the Rachitomi (I. c. p. 53). In 

 Laccocephalus the mesial process of the pterygoid suturates with 

 the lateral edge of the parasphenoid in a region that corresponds 

 to that from which the ascending process of the bone of fishes 

 has its origin, and cartilaginous extensions of the basisphenoid 

 are said {I.e. p. 54) to "seem to have passed outward above the 

 flat parasphenoid expansions to the epipterygoid and pterygoid." 

 At the hind end of the suture between the pterygoid and 

 parasphenoid there is a foramen which leads into a canal in the 

 parasphenoid and transmits the internal carotid artery. In 

 Ga'pitosaurus the mesial process of the pterygoid suturates both 

 with the parasphenoid and the exoccipital, and there is no basi- 

 pterygoid process. The quadi-ate ramus of the pterygoid is said 

 (Watson, 1919, p. 27) to form "a thin plate, rising nearly 

 vertically, to have a long and close connection with the supra- 

 temporal and squamosal. Its upper inner corner has a sutural 

 union with the prootic, with which bone and the supratemporal 

 it forms a large foramen leading forwards over the prootic and 

 epipterygoid to the anterior part of the skull. This opening 

 must transmit the vena capitis dorsalis and a lymphatic duct. 

 Just above its articulation with the parasphenoid and below the 

 prootic the inner margin of the quadrate ramus of the pterygoid 

 is notched for the passage of the vena capitis lateralis and the 

 seventh nerve." This part of the pterygoid of this amphibian 

 thus has to this part of the skull the topographical relations that 

 the ascending process of the parasphenoid of fishes has, or that 

 the piscine processus metapterygoideus would have if it were 

 to persist and acquire contact with the cranium after the 

 Proc. Zool. Soc— 1923, No. IV. • 4 



