arr. 16. TWO SQUALODONTS FROM MARYLAND—KELLOGG. 41 
g'. Premolars slightly compressed; crowns recurved, the enamel 
ornamented with longitudinal striae. 
3-3 1-1 5-5 7-7 
; C.——; pm. —; m. —. 
Gey io To. ag 66 
Width of rostrum at narrowest point, 50 mm.; width of rostrum 
at base, 184mm. Orbital apophysis of the supraorbital proc- 
cess of frontal pointed anteriorly. Mesorostral channel open. 
Mesethmoid forms a thick partition separating nasal pas- 
sages superiorly, sheathes the dorsal and lateral faces of the 
presphenoid in the narial region, fills in the large frontal 
fontanelle and thus contributes to the formation of a pair 
of foramina which lead from the cranial cavity to the meso- 
rostral channel, provides support for the vertex of the skull, 
and underlies the abbreviated nasals. Ascending processes 
of premaxillae extending posteriad to nasals. Supraoccipital 
wide, equaling nearly one-half of greatest width of skull 
across squamosals. Vomer appears in roof of palate as 
splintlike bone inserted between horizontal plates of the 
maxillae. Coronoid portion of mandible curved inward 
and distal portion outward; in consequence the alveolae 
shift with the postero-anterlor curvature of the ramus from 
a horizontal to a lateral position. Width of tooth bearing 
portion of the ramus, 19.5 mm. to 27 mm. Symphysis 
extends backward to second molar and approximates the 
upper margin of the ramus anterior to alveolae for the last 
premolar. Ulna possesses a well-developed olecranon proc- 
ess (Maryland)....... Squalodon calvertensis, new species. 
f?, About one-half of the true molars in each upper jaw with anterior 
and posterior cutting edges serrated by well-defined accessory 
cusps. 
g'. Accessory cusps on the cutting edges of molars closely approxi- 
mating each other; the four posterior molars unknown. Pre- 
molars slightly compressed; crowns lightly fluted. 
3-3 1-1 5-5 7-7 
Dental formula: 1. sie ; pm E, 
; ¢. —} pm. —; m. ——. 
3-3 1-1 4-4 ?-5+ 
Length of rostrum in advance of maxillary notch more than 
twice length of cranium posterior to notch. Width of rostrum 
at anterior extremities of maxillae, 40 mm.; width of rostrum 
at base about 115 mm. Orbital apophysis of the supraor- 
bital process of frontal truncated anteriorly (rather squarely). 
Mesorostral channel open. Nasalsrudimentary. Frontals 
forming a relatively broad strip across the vertex and not 
conspicuously overlapped by the ascending processes of the 
maxillae. Ascending processes of premaxillae extending 
posteriad to external narial openings, the distance approxi- 
mately equivalent to anterior breadth of exposed surface of 
frontals on vertex (Bavaria)..........-. Squalodon zittels. 
g?. Accessory cusps on the cutting edges of molars projecting freely; 
well-defined cusps present on both anterior and posterior edges 
of the posterior molars. Enamel surface of molar crown roughly 
sculptured or ornamented with coarse striae (New Jersey). 
Squalodon atlanticus. 
F?, Both edges of some of the molars not provided with sawlike cutting 
surfaces in addition to accessory cusps. 
Dental formula: 7. 
