GwBN descrive cosi la intima struttura dei denti di Phyllodus : « The 

 « osseous subitanee (a) is characterized by the terge , reticularly arrosto- 

 ( mosing medullary canaU without radiated cells in their interspaces which 

 c« are peculiar to the structure of the boncs and ossified ba>is of the teelh 

 « in fìshes. The dentine (b) consists of numerous close-set calcigerous tu- 

 '< bes and the clear-uniting subslance ; the tubes are characterised by their 

 ' straight and parallel course ; at the middle part of the piate they are di- 

 '< rected verlically to its piane, and at the margins , which are bent down, 

 « they incline so as to maintain the same relative position to that part of 

 * the snrface of the piate; their diameter docs not exceed Y li000 iU of an 

 « indi ; their subdivision into pencils of smaller tubes takes place nearer 

 « to tiie enamel than usuai. I could plainly discern the anastomoses of the 

 « divisions of the calcigerous tubes in some parts of the section. The 

 « Enamel (e) which as in the denticles of the Scarus and tnany other 

 « fìshes closely approximates in structure to the dentine, exhibits howover 

 « mudi less parallelism in the course of its component tubes in the Phyl- 

 « lodus ; but these are as numerous and distinct though somewhat more mi- 

 « mite than those of the true dentine » (1). 



Confrontala la struttura de denti de* Phyllodus con quella di Scarus , 

 Labrum, Chrysophris, Gyrodus,- Pycnodus etc, Owkn conclude che le analogie 

 maggiori sono con Scarus, e cosi propende a considerare Phyllodus come un 

 tipo estinto di Labroide affine a Scarus. 



GiEBEL successivamente adottò questo modo di vedere, e ripose Phyllodus 

 fra Labroidi (2). 



Quantunque nella Pakonlology dello stesso Owen (Ediz. del 1 SGO ) 

 si legga a pagina 1 49 : « The Ganoids in these ( tertiary ) formations are 

 « reduced to the genera Lcpidosleus and Arìpenscr ; but may have been re- 

 « presented by the palates with crushing teeth, from the Sheppy day , to 

 « which the names Pisodus and Phyllodus have been given » ; noi non par- 

 tecipiamo a questo dubbio ed accettiamo il ravvicinamento affacciato nella 

 Odonlography. 



Per togliere Phyllodus dalla famiglia dei Picnodonti (Ganoidi), ci vale 

 la struttura anatomica de' denti offrente più analogia con Scarus di quello che 

 con Pycnodus e Microdon , e ci valgono ancora le seguenti considerazioni. 



! Owen, Odotilor/rapln/ , pag. 1 ìO, Tav. .il 



ì GiEBEL, Fauna <lc.r Worwcll , rie. — OJontographic 1856, pag. 106. 



