246 W. K. GREGORY HOMOLOGY OF LACRIMAL AND ALISPHENOID 



served are due to the mammalian alisphenoids having retained certain 

 relations which were already established in the Cynodonts. 12 



Mutability of Names in reptilian Osteology 



The questions thus briefly touched oh have, I think, more than an aca- 

 demic interest to paleontologists. They raise the question whether pale- 

 ontologists will permit the nomenclature of the reptilian skeleton to be 

 indefinitely upset and confused. The naming^of elements in lower verte- 

 brates in accordance with their supposed homologies in mammals has in- 

 deed been the historic process, but it is having the same disturbing effect 

 on anatomical nomenclature as the search for prior names has had on 

 systematic nomenclature. Gaupp, as we have seen, shifts the name lacri- 

 mal from one bone to another, and von Huene performs the same kind 

 office for the orbito-, ali-, and presphenoids. 



Supposing Watson is right in holding that the mammalian alisphenoid 

 has been derived from the reptilian pterygoid, plus epipterygoid, and that 

 the mammalian pterygoids in turn have been derived from the ectoptery- 

 goids; shall we therefore transfer the name pterygoid from the ptery- 

 goid to the ectopterygoid, and shall we call the pterygoid alisphenoid? 

 Would it not be more sensible to say that the reptilian pterygoid was still 

 the pterygoid; that the ectopterygoid was still the ectopterygoid, no 

 matter what they subsequently gave rise to in the mammals ? 



Similarly, would it not be well for those who believe that the reptilian 

 quadrate was transformed into the mammalian incus to continue to apply 

 these names in the respective classes ? 



B I . 



Conclusions 



(1) The prefontal of reptiles is not homologous with the lacrimal of 

 mammals. 



(2) The lacrimal of reptiles is homologous with the lacrimal of 

 mammals. 



(3) The alisphenoids of dinosaurs, etcetera, are not homologous with 

 the orbitosphenoids of mammals, but in part with the alisphenoids of 

 mammals. 



(4) The pterygoids (including the epiptervgoids) of reptiles probably 

 gave rise to the alisphenoids of mammals (Watson). 



(5) Transference of names from one element to another is highly ob- 

 jectionable. There is no practical necessity for invariably applying the 

 same name to homologous elements in different classes. 



12 This subject is more fully discussed in my forthcoming paper in the American 

 Journal of Morphology. 



