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AXXAL8 NEW YORK ACADEMY OF SCIEyCES 



pomidag offer a txansitional stage leading back to liie simple rhombic type, 

 since in tbem the scales, although scnlptitred. are more or less rhomboidal 

 and overlap bnt slightly. The Holoptychiida moreorer have excessively 

 specialized dentrodont teeth. 



The OsieolepidaB and BhizodontidaB are pike-like nshes (Fig. T), with 

 elongate bodies and powerful candaL dorsal aad anal fins. — h::h *he- zz-ij 

 have us^d both in sndden rushes at their prey and in hol_:_^ :_r— s-.Tes 

 stilL 



Fig. 7. — R^^ioraiion of MegaUchthy^. After E. D. Weliburn 



A progressiTe osteolepid rhipidistiaii of the Coal Measures. 



Skolt-zoof : E, ethmoid : Xa, nasal : X. nostril ; AF_. "ajttterior frontal" [ectethmoid, 

 septoraaxilLaiT] : Fr^ frontal : PF, postfrontal : Pa. parietal : ST. ST. "supra temporals" 

 [dermosapraoceipital, tabnlaxe]. 



Orbxfcal series: JLO, "anterior orbital'" [iacrTmalj ; SOjSO_. "suborbitals" [jogal] ; PO, 

 postorbitaL 



Temporal series: X^ "cheek plate" [anterior portion of true squamosal] ; X', "che^ 

 plate" [quadratojngal] ; SQ, "sgnamosal" [supratemporal. pterotic] : P.O. preopercolom 

 [posterior portion of true squamosal]. 



Opercolar series: Op. operculum; So, snboperculum. 



Gular series: LjJjj, lateral jugular [lateral gnlars] : the antero-lateral gnlars may 

 pofaaps give ri?e to the angolare of Tetrapoda ; J, gnlar : JL/.. ''anterior jugular" median 

 golar. 



fj^^rtiai series: Pnx. premaxillarv : Mn, maxillary : D, dentary : IDJD, infradentaries 

 [splenial, preangular] ; AG, angular [ ? supraangular] . 



jfftonyigr girdle: I, CI, **infraelaTicular" [clavicle] ; CI, "clavicle" [deithrom] ; 8CL, 

 •"supraclavicle" [ snpracleithrom] . 



Fins: B.S. basal scales; RS, ridge scales; FS, fulcral scales: P. Pi S, propterygial 

 scales : Jf JPt jS,. metapterygial scales ; AS, anal scales. 



Adaptati<m to predatory habits is indicated by the wide gape and strong sharp teeth, 

 and by the pike-like body, with powerful median and pelvic fins, which are placed near 

 tbe posterior end. The broad, stout pectoijil fins would be useful chiefly in suddenly 

 tlii'<liiiiL a forward rush and turning the head. 



The Holoptychiidae on the contrary were relatively deep-bodied, carp- 

 like forms, with weaker, longer and more flexible fins. The related 

 GlyptopomidsB were more primiiive in having rhombic scales and were 

 pike-like in form, with powerful caudal, dorsals, anals and T)elvics. 



What were the habits and form of the common ancestors of all these 

 &inilies? Probably they were comparatively short-bodied forms, with 

 smaU. granular rhombic cosmoid scales, two dorsal fins, a heterocercal 

 caudal, short lobate pectorals and barely lobate pelvics; the lepido'trichs 



