ZOOLOGY. 



The Paroccipital of the Squamata and the Affinities of 

 the Mosasauridae once more. A rejoinder to Professor 

 E. D. Cope. — I. The paroccipital. — In 1870, Cope 1 designated the 

 occipital externe, Cuvier, paroccipital, Owen with Huxley's name 

 opisthotic, and homologized it with the squamosal of the Lacertilia and 

 Ophidia. This opinion is held up in 1894 and in September, 1895, 2 

 but for the name opisthotic the name paroccipital is then used. On 

 the other side, it is admitted by everybody else that the paroccipital, 

 Owen (opisthotic, Huxley), which is free in the Testudines, is united 

 with the exoccipital in the Lacertilia ; the posterior portion of this bone, 

 which is visible from behind, has been called the paroccipital process ; 

 in it? anterior portion where it reaches the basioccipital it contain* the 

 posterior semicircular canals. I have stated in my last note (Am. 

 Nat., Nov., 1895) that in young Sphenodons the paroccipital is free 

 from the exoccipital exactly as in the Testudines and that Siebeurock 

 has proved without question that the outer portion of the exoccipital 

 of the Lacertilia, which lodges anteriorly the posterior semicircular 

 canals, represents the same element. The paroccipital process of the 

 exoccipital in Sphenodon is, of course, identical with the paroccipital 

 process in the Lacertilia. 



To this, Prof. Cope replies : " Baur asserts that the Bocalled parotic 

 process [I said paroccipital process] of the exoccipital which supports 

 the quadrate in the Squamata is the same element as that termed opis- 

 thotic by Huxley. This I deny, and believe that in this it is Baur 

 and not myself who has fallen into error. Siebenrock, instead of assert- 

 ing this to be the case, denies it in the following language :f * It is not 

 the processus paroticus of the pleuroccipital (exoccipital) which is 

 homologous with the (paroccipital, Owen), opisthothic Huxley, but 

 the portion anterior to the foramen nervi hypoglossi superius which pro- 

 tects the organ of hearing.' Siebenrock here uses the names of Owen 

 and Huxley as refering to the same element, bat he make* the clear 



1 Cope, E. I). On the Homologies of the ( )piethotic Bone, Amer. Asso. Adv. 

 Sc., XIX. 



1892. The Osteology of the Laeertilh 

 May 10, 1892, pp. 185-211. 

 t Italics are mine. 



