1894.] 



NATURAL, SCIENCES OF PHILADELPHIA. 



41 



Fig. (j. Side vit'w of skull of cod-fish. 



turtle and described by Cuvier -' as mastoideus and occipital externe, 

 bv Owen "' as mastoid and paroecipital, and by Huxley '''^ as squa- 

 mosal and epiotic in tlie tisli and squamosal and opisthotic in 

 the turtle? In reply to such query, in the judgment of the author 

 the bone, No. 8, (Figs. 5, 6, 7, 8) described by Cuvier as mastoidien 

 and bv Owen as mastoid in the skull of the lower vertebrates, 

 should be regarded as it is by Huxley and most modern 



anatomists, as the homologue of the 

 squamosal (Fig. 3, s) of the tenqjoral 

 of iMau. The bone No. 4, (Figs. 5, 

 8, the occipital externe (perch) Cu- 

 vier, the paroecipital of Owen, the 

 epiotic of Huxley in fish, opisthotic 

 in turtle, is not, however, represent- 

 ed as a distinct bone in the skull of 

 Man but as the "eminentia aspera"^* 

 of the occipital bone or the "scabrous ridge extended from the 

 middle of the C(jndyle towards the roots of the mastoid process." ^^ 



The name occipital externe, or its 

 English equivalent external occipi- 

 tal, may as well then be retained 

 for the bone No. 4 as simply ex- 

 pressing the fact that there exists in 

 • Fig. 7. Skull of python. the skuU of the lower vertebrates a 



bone lying external to the supra and ex-occipital irrespective of any 

 preconceived hypotheses. The names paroecipital and epiotic should 

 be discarded, as the former implies that the bone No. 4 is the para- 

 pophysis of the first cranial vertebra, the latter that it is the 

 honnjlogue of the special centre of ossification of the mastoid in Man. 

 It has been urged iu favor of the bone No. 4 being called the epi- 

 otic in the fish that it eaters into the formation of the ear-chamber, 

 its inner surface being excavated for the reception of part ot the 

 posterior and external semicircular canal. Such argument, however, 

 loses all force when it is remembered that the exoccipital is similarly 



^^ Histoire Naturelle des Poissons, Tome 1, p. 236. 

 2^ Anatoniv of Vertebrates, Vol. 1, p. 97. 

 23 Op. cit. p. 174. 



^^8. T. H. Soenimeriiis "De Corporis Himmui Fabrica," T. 1, 1704, p. 105. 

 25 Alexander Monro. "The Anatomy of the Humane Bones," Edinburgh, 1732, 

 110. 



4 



