38 PROCEEDINGS OF THE NATIONAL MUSEUM vol. GO 



EXPLANATION OF PLATES 



Eurhinodelphis bossi, new species. Type, Cat. No. 8842, Section of Verte- 

 brate Paleontology, United States National Museum. Calvert formation, 

 western shore of Chesapeake Bay, about 2 miles south of Chesapeake Beach, 

 Calvert County, Maryland. Collected by Norman H. Boss, August, 1918. 



Plate 1 



Type skull of Eurhinodelphis bossi, new species. About one-sixth natural 

 size. Fig. 1. Dorsal view. Fig. 2. Ventral view. Abbreviations: Bo., basioc- 

 cipital ; C, condyle ; Ex. 0., esoccipital ; Fo. c, condyloid foramen ; Fo. inf., 

 infraorbital foramen; Fo. I. p., foramen lacerum posterius; Fo. max., maxillary 

 foramen ; Fr., frontal ; Ha., hamular process of pterygoid ; Ju., jugal ; La., lach- 

 rymal ; Max., maxilla ; Mes., mesethmoid ; Na.., nasal ; Op. c, optic canal ; Pal., 

 palatine; Pmx., premaxilla ; Pt., pterygoid; So., supraoccipital ; S. or. pr., supra- 

 orbital process of frontal ; Si. pr., styliform process of jugal ; V., vomer ; Zyg., 

 zygomatic process of squamosal. 



Plate 2 



Lateral view of type skull of EurhinodelpMs bossi, new species. About one- 

 sixth natural size. 



Plate 3 



Dorsal view of type mandible of EurhinodelpMs bossi, new species. Al)out 

 three-tenths natural size. 



Plate 4 



Posterior view of type skull of EurMnodelphis bossi, new species. About 

 one-half natural size. 



Plate 5 



Ventral view of skull of EurhinodelpMs bossi. Individual 2, Cat. No. 10714, 

 United States National Museum. About five-sevenths natural size. View show- 

 ing foramina within the tympano-periotic recess and the relations of the 

 various elements composing the ventral face of the skull. The external re- 

 duplication of the pterygoid and the orbitosphenoid are missing. Hence the 

 outer wall of the nasal passage is also missing. Abbreviations : Al., alisphenoid ; 

 Bo., basioccipital ; Bo. pi., descending plate or falcate process of the basioc- 

 cipital ; C, condyle ; Ex. o., exoccipital ; Fo. inf., infraorbital foramen ; Fr., fron- 

 tal ; Ju., jugal; La., lachrymal; Max., maxilla; Op. c, optic canal; Pah, pala- 

 tine ; Pt., pterygoid ; S. or pr., supraorbital process of frontal ; Sq, squamosal ; 

 v., vomer ; Zyg., zygomatic process of squamosal ; 1, carotid canal ; 2, passage 

 for mandibular branch of trigeminal nerve; 3, furrow for mandibular branch^f 

 trigeminal nerve ; 4, foramen lacerum medius ; 5, jugular foramen or foramen 

 lacerum posterius, compartment for nerves; 6, jugular foramen or foramen 

 lacerum posterius, compartment for vein; 7, condyloid foramen or hypocrlossal 

 canal in jugular incisure. 



Plate 6 



Views of scapula and vertebrae of EurMnodelphis bossi. Fig. 1, dorsal or 

 external view of left scapula (about three-sevenths natural size) ; Fig. 2, posterior 

 epiphysis of fifth caudal (about two-fiftha natural size) ; Fig. 3, anterior view of 

 fifth cervical (about one-half natural size) ; Fig. 4, ventral or internal view of 

 left scapula (about three-sevenths natural size) : Fig. 5, internal surface of 

 epiphysis of an anterior caudal (about two-fifths natural size) ; Fig. 6, posterior 

 view of fifth cervical (about one-lialf natural size). 



