ALISPHENOID AND ORBITOSPHENOID 243 



The alisphenoids of mammals in the developing cartilage skull are rep- 

 resented by a pair of winglike outgrowths, called the alee " temporalis, 

 which project widely from either side of the basisphenoid. These tem- 

 poral wings lie below the roots of the trigeminus nerve and both in front 

 and outside of the carotid foramina. Accepting ontogeny as in some 

 measure an indication of phylogeny, Gaupp concludes that the mamma- 

 lian alisphenoids arose outside of the primary brain-case and have only 

 secondarily grown up around the outer side of the fifth nerve, and thus 

 have come to shut in the open space between the auditory capsule and the 

 cartilage orbitosphenoid. In the chondrocranium of the lizard the 

 basipterygoid processes of the basisphenoid, like the alae temporalis of 

 mammals, project widely from either side of the cartilaginous basisphe- 

 noid ; they also lie below the roots of the trigeminus and in front of the 

 foramina for the carotids. Hence Gaupp homologizes these basipterygoid 

 processes in the lizard with the cartilaginous alisphenoid wings of mam- 

 mals. These basipterygoid processes he supposes to have become turned 

 upward, so that they covered the roots of the trigeminus externally; by 

 further upgrowth of the replacing bone they covered the temporal region 

 of the skull. 



If the reptilian basipterygoid processes alone represent the cartilagi- 

 nous alisphenoids of mammals, as Gaupp maintains, then it follows that 

 that pair of bones in the temporal region of reptiles which have been 

 called alisphenoids must represent some other elements. Doctor Von 

 Huene 9 accepts Gaupp's views and applies them in the field of paleon- 

 tology. He says (1911) that the name alisphenoid should no longer b-t 

 applied to Sauropsidan skulls; that the bone formerly called alisphenoid 

 in the Sauropsida is identical with the orbitosphenoid of mammals. Con- 

 sequently in all his recent papers on fossil reptiles the bones usually 

 called alisphenoids- are lettered orbitosphenoids, the lacrimals are called 

 adlacrimals, and the prefrontals are called lacrimals. 



Gaupp's conclusions regarding the alisphenoid were based very largely 

 uii a comparison of lizard and mammal in embryonic stages without ref- 

 erence to paleontological evidence. In order to test Gaupp's conclusions. 

 I have studied the composition and elements of the brain-case in many 

 recent and fossil reptiles, especially Cotylosaurs, Cynodonts, Dinosaurs. 

 Crocodiles, Sphenodon, etcetera, primarily from specimens, but also as 

 they are described in recent papers by Williston, Broom, von Huene, 

 Watson, and others. T have come to directly opposite conclusions to those 1 

 of von llucnc and Gaupp, although at first inclined (o accept them. 



9 Beltrliee /nr Kenntnlss and Beurtellung der Parasuchler. Kokon's Qeol, u. Pal. 

 Abhandl., n. F. Bd. 10, 1911, p. 43. 



