A treatise on zoology . Fig. and teeth of the Eagle-Ray, ilyliobatis aquilo, L. (After Owen.) Mijliobatis, Cuv., and Aeohatis, M. and H., warm seas ; to Eocene,Europe and X. America. Pronviliobatis, Jaekel ; Eocene, Italy. Sub-Family 2. Dicerobatixae. AVith paired cephalic-fin teeth, which are closely set in many rows, may be small and almost RAJIFORMES 167 imifonn, or some niidclle rows may be enlar<fecl (Figs. 131, 132). InCerato2)tera they are absent from the upper jaw. IHcerohatis {Cephalfqjtera), Blainv., Ceratoptera, M. ami H., andlihinoptera • warm seas; the la
A treatise on zoology . Fig. and teeth of the Eagle-Ray, ilyliobatis aquilo, L. (After Owen.) Mijliobatis, Cuv., and Aeohatis, M. and H., warm seas ; to Eocene,Europe and X. America. Pronviliobatis, Jaekel ; Eocene, Italy. Sub-Family 2. Dicerobatixae. AVith paired cephalic-fin teeth, which are closely set in many rows, may be small and almost RAJIFORMES 167 imifonn, or some niidclle rows may be enlar<fecl (Figs. 131, 132). InCerato2)tera they are absent from the upper jaw. IHcerohatis {Cephalfqjtera), Blainv., Ceratoptera, M. ami H., andlihinoptera • warm seas; the latter to Eocene, Europe. Family Psammodoxtidae. Known only from fossil teeth, whichare transversely elongated, flattened, and adapted for grinding. They are. Teeth of llhinopteiv pohiiidon, Gtlir.(After Giiiither.) Fig. 133. Tootli of rolt/rhizodus imsilUs,MCoy; Carboniferous Limestone,Armagh. (After JlCoy.) c, outergrinding surface ; r, basal root. closely set in longitudinal rows, somewhat as in the Myliobatidae, withwliich this family is generally associated. CopoduS; Davis, Fsammodus, Ag. ; Lower Carboniferous, Euroi^e andX. America. Ardmeohatis, Xewb. ; Lower Carboniferous, X. America. IXCERTAE . Family Petalodontidae. These palaeozoic Selachians are chieflyknown from remains of the dentition, which is much specialised. In thecase of Janassa it has been ascertained that the body was depressed andexpanded, with large pectoral fins reaching forward and perhaps fusing withthe head (Miinster, Jaekel [240]). The jaws were wide and strong,l)earing powerful grinding teeth set one behind the other in regular the old teeth remained to support the newer growing upfrom behind. As a rule, each tooth has a distinctly marked
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