NATURAL SCIENCES OF PHILADELPHIA. < 



TRETOSPHYS Cope. 



Proc. Acad. N. Sci., Phila., 1868, p. 18C, 100. 

 Dclphinapierus " Lesson," Cope, Proc. A. N. Sci. Phila., 18G8, 189. 



Tlie species of this genus I foruierh' referred to Lesson's genus as above, 

 the Beluga of Gray, as one of the ^^^w genera of existing Delphinidre, in which 

 the cervical vertebrae are all similarly distinct. I could find no characteristic 

 feature by which to separate the two. I am, however, now entirely able to 

 separate the miocene from the recent species, in respect to generic structure. 

 The new genus is defined as follows, so far as known : 



(Jervical vertebra; elongate as in the seals, and all distinct. Their di- and 

 parapophyses all united and embracing a small foramen for the vertebral ar- 

 tery. 



In the existing genus the cervical vertebrae are thin and disc like, and none 

 but the anterior one or two embrace a foramen, and that rarely. In the genus 

 Tretosphys the structure is quite similar to that seen among the seals, and has 

 given the species a physiognomy quite distinct from the modern dolphins. 

 They have evidently had a well marked neck, endowed with considerable 

 flexibility. This constitutes an approach to the Zeuglodonta, which is 

 still more marked in the genus Priscodelphinus. In this also there is the 

 same elongate series of cervical vertebra?, and well enclosed cervical canal. 



The species of the genus may be defined briefly as follows : 



I. But few and only posterior caudals Avith venous foramen at base of dia- 

 pophysis. 



a. Posterior lurabars three-sixteenths or less, longer than wide before dia- 

 pophyses. 

 ** Neural canal with obtuse epapophysial ridge. 

 Articular surface with incised median impression, central rugulose disc, and 

 broad circumference with raised concentric stria? ; lumbars straight and strong- 

 ly keeled below ; caudals short and broad ; large T. lacertosus. 



Articular surface without striic, and with a deep punctiform median impres- 

 sion which is below the middle; most lumbars concave below; caudals more 



elongate, 35 lines long in young : smaller T. grandaevus. 



Articular face without strise, and with punctiform impression (on caudal) ; 



caudal stouter, 24 lines long in adult ; smallest T. gabbii. 



aa. Posterior lumbars i longer than width before diapophyses. 

 Articular face with punctiform impression, and no raised striae ; an epapo- 

 physis ; caudal narrow, 39 lines long in adult T. uraeus. 



II. An anterior caudal with vascular foramen at base of diapophysis. 

 Articular face of lumbar with weak incised impression, smooth ; below 



weakly keeled ; length in adult 21 lines; the smallest species. 



T. rcschenbergeri. 

 The species which I described as Delphinapterus tyrannus (Proc. A. N. Sci. 

 Phila., 18G8, 189,) probably belongs to the toothless whales, and would cor- 

 respond in size with the Eschriclitius pu si 11 us. The collation of differ- 

 ent parts of each of these species must be left for future opportunities. The 

 vertebrae are distinguished by having the neural canal without epapophysis, 

 the articular face with open median impression, and no strife. The epiphysial 

 ridges are much interrupted and slightly tuberculiform. 



Tretosphys lacertosus, Delphinapterus [Tretosphys) laceriosus and D. hnw- 



khisii Cope, 1. c. p. 190. 



This species is known by portions of two individuals from Charles Co., 

 Marj'land, of one from the mouth of the Patuxent, and of five at least from the 

 marl pits of John Hummel, Henry Ware and others, near Shiloh, Cumberland 

 &b., N. J. Portions of crania with teeth, etc., are mingled with the vertebrae, 

 and furnish material for a partial analysis of the characters of the species. 



1869.] 



