1894.] NATURAL SCIENCES OF PHILADELPHIA. 37 



passend 0.s oceipitale extenuuii genaunt vvordeu ist. Beide Knochen- 

 stiicke nun, die zusamnieiigenomnien eigentlich niclits anderes als 

 das Felseubeiii der hohern Thiere vorstellen." 



About the s-aine time the late Professor Owen'", in referring to the 

 views of Kerckringius as to there being "tria petrosa ossis distincta 

 ossicula," called attention to the primary independence of the base 

 of the processus mastoideus as " a fact of much more significance 

 than its brief and transitory manifestation would lead the author to 

 divine." He further observed that "in the cold blooded vertebrates 

 the mastoid retains with a few exceptions its primary embryonic dis- 

 tinctness as an independent element of the skull." It should be 

 mentioned in this connection, however, that as Professor Owen re- 

 garded the bone now considered in the lower vertebrata as the 

 squamosal to be the homologue of the special centre of ossification of 

 the human pars mastoidea, he called it accordingly the mastoid. 



In 18G1 the view of Meckel as to the original distinctness in the 

 embryo of the three parts of the petromastoid portion of the tem- 

 poral bone was confirmed by Kolliker" in his description of the de- 

 velopment of that bone in Man. 



Finally, Professor Huxley in his lectures as Hunterian Professor 

 at the Royal College of Surgeons of England, in 1863, and em- 

 bodied substantially in his " Lectures on the Elements of Compara- 

 tive Anatomy," '■ developed at length and in detail the view that the 

 petromastoid portion of the tempoi'al bone in man is developed from 

 three centres as described by Meckel and K()lliker, and further that 

 these three centres are re})resented in the lower vertebrata as more 

 or less distinct bones as hekl by Rathke and Owen. 



The two bones described by Rathke as forming in the turtle the 

 "felsenbein" were named by Prof. Huxley the prootic''^ and opistho- 

 tic"; that regarded by Owen as the mastoid was considered by Prof 

 Huxley to be the squamosal'', and the "specially mastoid" part of 

 the "pars mastoidea" the "scutum ovale referens" of Kerckringius 

 was named by Prof. Huxley the epiotic'". 



"•' Ui'bei-(lit> Eiitwickcluii^ der Sehildkrotcu. BrauiischweiK, 1S48, p. 52. 



'"Ou the Archetype aiul Uumologies of the Vertebnite Skeleton. London, 

 1848, p. 29. 



'• Eutvvickhuig.-igeschichte des Menschou imd der Hoheren Thiere. Leipzig, 

 p. 32[». 



1- London, 1864. 



••^ Op. cit. p. 222. 



'^Op. cit. p. 222. 



'»Op. cit. p. 230. 



"'Op. cit. p. 155. 



