2GG 



SUrn.EMENT TO THE EXTINCT BATJiACHIA 



of tbat species in wliicli the cranium has the same size, the median pectoral plate is narrower and more prolonged 

 longitudinally, and exhibits tubercles and a few ridges near the circumference, but no cross-like figure. 



Dedicated to Prof. Alexander Winchell of the New York University, at Syracuse, author of the "Sketches 

 of Creation," etc. 



PTYONIUS PECTINATUS, Cope 



Snuropleura pectinatn, Cope, Proceed. Acad. Nat. Sci., Phila., 1808, 218 ; O'esloceplialus pectinatus, Transac. 

 Amer. Philos. Soc, 1869, XIV, p. 20. 



PTYONIUS SERRULA, Cope. 

 Proceed. Amer. Philos. Soc, 1871, p. 177. {O'estoccphaliis) 



Represented especially by a single almost comiDlete specim.en, and perhaps by another originally referred to 

 the P. pectinatus. It is only half as large as that species, but displays a more complex sculpture of the pectoral 

 shields, indicating that it is not immature. The tail is relatively longer. 



The remains of the head indicate a trigonal outline ; but the muzzle is lost. The pectoral shields are narrow 

 and elongate, both median and lateral a little wider behind. The median has a considerable smooth anterior pro- 

 longation. Its surface is near the middle sharply reticulate-ridged, then closely radiate-ridged to the margin. The 

 lateral shield is reticulate-ridged behind and sends out radii, those on the anterior part sub-parallel. The triangular 

 hcemal spines begin far forward; with the neui'als, they are rather elongate-deltoid in form without the distiuct 

 peduncle seen in P. jjeeiiiiatii.i, but instead, a short concave or cresent shaped base from the concavity of which the 

 sculpture rises. This consists of ridges which extend beyond the intermediate spaces, like teeth. Abdominal rods 

 hair-like. Ribs distinct. Remains of limbs not discernible. 



In the second specimen alluded to, weak limbs are seen on each side of the posterior part of the abdominal 

 cavity. On the right a moderately stout femur is given oif, which is followed by a broken tibia and fibula, and then 

 by five closely api^ressed metatarsals. The last are 2-5 as long as the space between them and the femur, beyond 

 them a few slender phalanges are moderately distinctly defined. The tibia is more distinct on the left, but thei-e are 

 no tarsus nor phalanges; some of the metatarsals remahi. Length of limb to end of metatarsals equal to five juxtaposed 

 vertebrai measured along the edge of the neural spines. The limb, especially the foot, is slender. In this specimen 

 there are ten neural spines included in a length of half an inch. 



lu the typical specimen twelve neural spines are included in a half inch. The dorsal vertcbrie are somewhat 

 dislocated in the anterior region, nevertheless it appears that the length from the front of the pectoral shield is 

 contained twice in the length of the tail ; in the smallest example of S. 2)ectinatii, it enters the same .75 of a time, 

 though perhaps a very little should be added for the missing extremity. 



M. 



Length of type from anterior edge of pectoral shield, 0.085 

 Length of median pectoral plate, 0.006 

 Width of neural and hasmal spines at first caudal vertebi-a, , .0045 



" " '« " at middle of tail, .0040 



OiisrOCEPHALUS, Cope. 



Proceed. Acad. Nat. Sci. , Phila., 1808, p. 218. Transac. Amer. Philos. Soc, XIV., p. 16. SauropUura, pt. 

 Proceed. Acad. Nat. Sci., Philada,, 1808, p. 217. Proceed. Amor. Philos. Soc. 1871, p. 41. 



Another genus resembling in its fan-like haemal and neural spines of the tail, 

 the European form Urocordylus, and dilfering from it as Ptyonvas does, i. e. in the 

 rod-like abdominal scales, and the well developed ribs. Its form is long and snake- 

 like, and it thus resembles OiMderjpeton, Huxl. But in the latter there are no limbs, 



