NATURAL SCIENCES OF PHILADELPHIA. 193 



MEGAPTERA Gray. 



Mkgaptera EXP ansa Cope. 



This species is based on numerous vertebrae from the Thomas collection, 

 several trom the Nomini Cliffs, Westmoreland county, Virginia, presented to 

 the Academy by my friend Oliver N. Bryan, of Charles county, Md.^ and by 

 some in the Academy's Museum from Virginia. 



The cervicals have a greater antero-posterior diameter than those of the 

 Eschrichtius species, but show quite similar di- and parapophyses. They 

 are, however, not at present in my possession, and their full description must 

 be postponed for a time. 



There are also ten dorsals and several lumbars and probably some cervi- 

 cals from the same collection. The former have a broad and capacious 

 neural canal, and the diapophysis is given off in all from the neural arch. 

 In the lumbars this process is of course given off lower down, but in them it 

 is flatter than usual. The centrum has somewhat the form of some of those 

 of Doryodon, being broad and of little antero-posterior diameter. The 

 articular faces have a transverse subcordate outline, being flat above. The 

 basal face without keel. The form of the epiphyses indeed approaches sub- 

 trigonal. 



In. Lin. 



Length anterior dorsal 2 9 



Height articular face 2 8 



Width " " 4 



" neural canal 1 9'7 



Length median dorsal 3 2-5 



Height articular face 3 05 



Width " " 3 7 



" neural canal 14-5 



The size of this species is quite comparable to that of the Eschrichtius 

 p u s i 11 us, being one of the smaller species. The elevated position of its 

 diapophyses disiinguishes it from all the Squalodons. 

 The extinct species of Balaenidai of the United Htates are the following: 



Megaptera expansa Cope. 



Eschrichtius cephalus Cope. 



Eschrichtius leptocentrus Cope. 



Eschrichtius pusillus Cope. 



Bal^noptera prisca Leidy.- 



Bal-«noptera pala:atlaxtica Leidy. 

 There is no evidence that either of the two last named species are true 

 Baltenopteri. They may be Eschrichtii, but cannot at present be referred to 

 those known as above. 



It is to be observed that none of the Miocene species exhibit the dimen- 

 sions possessed by the largest existing species, while several of them are 

 smaller than the least of those of modern seas. The present period would 

 appear, with present information, to be that in which these monsters have 

 attained their greatest bulk. 



The recent Balienidaj of our coasts are the following : 



Bal^na mysticetus Linn., Polar Sea. 



Bal^ena cisarctica Cope, Temperate Sea. 



Balaina cullamach Cham., North Pacific. 



Agaphelus glaucus Cope, Temper. Pacific. 



Agaphelus gibbosus Erxl., Temp. Atlantic. 



Megaptera osphyia Cope, " " 



Megaptera longimana Gray, Polar Seas. 



Eschrichtius ? robustus Lillj., Temp. Atlantic. 



BAL.EN0PTERA ROSTRATA Fab., North Atlantic. 



SiBBALDius LATiCEPS Gray, North Atlantic. 

 1868.] 



