34 PROCEEDINGS OF THE ACADEMY OF [1894. 



lu the fifth chapter of his Osteogeuia Foetorum/ published in 

 1G90, Kerckringius observes : " Ossis petrosi pars ilia, quae pro- 

 cessum mammilluarem constituit, terna de novo acquisivit ossicula; 

 unum pyriforma, acutiore, sui parte squamoso annectitur; alterum 

 scutum ovale referens, magnitudine, priori vix cedens, media cartila- 

 gine ab eo separatur; uti &c. , tertium ab utroque, quam vis hoc 

 magnitudine neutri sit aequiparandum, vix aciculae majoris caput 

 adaequans sunt autem eo situ ordiue collocata, queni tabula foetus v, 

 mensium, usurpata oculis facilius ad mentem quam verba transmit- 

 tet. . . . Constat ergo os temporuni hoc quinto mense sex dis- 

 tinctis ossiculis; osse videlicet, squamoso, anulo, osse interuam 

 civitatem efformante Ac, tribus notabilibus quae hoc mense ex orta 

 esse diximus. Sexto mense pyriforrae, &c. ovale scutiforme coalue- 

 runtinuuum; tertium uon nihil auctum est magnitudine. 

 Septimo mense jam tertium illud ossiculum duobus mense superiors 

 inter se coalitis accessit." 



That these three centres of ossification, viz., the "pyriforma," 

 "scutum ovale" and "tertium" do not correspond exactly to the 

 prootic, epiotic and opisthotic centres in the sense in which these 

 terms are used by modern anatomists, appears from the text of the 

 latter part of the passage quoted, beginning " constat ergo," the tem- 

 poral bone being said to consist at the fifth month of six distinct os- 

 sicles, which would be impossible if two of the "tribus notabilibus" 

 coalesced to form the "osse internam cavitatem efformante," which, 

 however, as. we shall see hereafter, they do a little later. That by 

 the "osse internam civitatem efformante" is meant that part of the 

 pars petrosa developed before and independent of the appearance of 

 the three distinct ossicles becomes evident from the description of the 

 state of the development of the temporal bone at the previous or 

 fourth mouth, Kerckringius stating that the bone at the end of that 

 month consists of three ossicles : "annulo, " "osse squamoso" and 

 "illo jam commemorato," the latter being the " osse internam " or 

 that part of the pars petrosa developed at that period. ' ' Quarto 

 mense mirum visu, quam cito & quanto perfectione os squamosum 

 magnam partem factum sit osseura. Os petrosum jam rubicunda 

 cartilaginesignavit cavitatis suae formam orgauorum audituscapacem, 

 nihil tamen adhuc praesefert osseum, praeterquam uuam in longitudi- 



1 Theochjii Kerckriugii, Osteogeuia Foetuum. Bibliotheca Anatomica, T. 

 II, Genevae, 1685. 



