93 SYSTEMATIC PALEONTOLOGY 



Occurrence. — Calvert Formation. Plum Point, Charles county 

 near the Patuxent river, Chesapeake Beach. 



Collections. — Maryland Geological Survey, Philadelphia Academy of 

 Natural Sciences, Museum of Comparative Zoology. 



UNDETERMINED SELACHIAN REMAINS. 



Under this head a hrief reference may be made to detached vertebrae 

 and fragments of Selachian armor, such as dermal tubercles and spines, 

 which are occasionally met with in Miocene strata. As a rule, the par- 

 tially calcified vertebrae are not well preserved, and worn examples are 

 quite impossible to determine. An exceptionally perfect centrum from 

 the Calvert formation at Plum Point is represented in Plate XXXI, 

 Figs. 4a, 4b, and this appears referable with tolerable certainty to the 

 genus Carcharodon. Although the presence of Raja, Trijgon, Myliohatis, 

 etc., is indicated by other remains, no vertebrae of the Batoid type have 

 been found in this state, and even Teleostome vertebrae are rare. 



The spine shown in Plate XXIX, Fig. 4, has already been noticed in 

 the discussion of Myliohatis remains {v. supra, p. 73). Less perfect 

 spines of equally large size from the Miocene of Eichmond, Virginia, 

 are described by Leidy,^ and referred by him rather doubtfully to the 

 genera Trygon and Myliohatis. This author also describes in the same 

 place, and from the same locality as the last, a dermal scute of Acipenser 

 ornatus, and jaw-fragments of Protautoga conidens, but neither of these 

 forms are known to occur in Maryland. 



Subclass TELEOSTOMI. 

 Order ACTINOPTERYGII. 



The only species of bony fishes recorded from the Miocene of this 

 state is " Sphyra^na speciosa Leidy," " represented by a single laniary 

 tooth from Charles county, of which a figure is given in Plate XXXII, 

 Fig. 16. This and an allied form described by Cope under the name of 

 Sphyrccnodus silovianus occur in the Miocene of New Jersey in com- 



iContrib. Extinct Vert. Fauna W. Territ. (Kept. U. S. GeoL Surv. Territ., vol. i, 

 1873, p. 353, pL xxxii, tigs. 53-.55). 



2E. D. Cope, Proc. Acad. Nat. Sci. Pliila., vol. xix, 1867, p. 143. 



