490 PROCEEDINGS OF TEE NATIONAL MUSEUM. tol.38. 



nounced than thai found in the living alligators. Another alligator- 

 like character is seen in the entire exclusion from this view of the 

 posterior nostril, due to its position below the opening of the eusta- 

 chian canal and in advance of the posterior border of the pterygoids, 

 from which it is partitioned off by a si rong bridge of hone 1 2 mm. wide. 



The exoccipital is pierced by four foramina. Of these, three are 

 close together a little above the floor of the foramen magnum PI. 

 26. Beginning with the most posterior, they are (XII) foramen for 

 the exit of the hypoglossal nerve (X) foramen for the pneumogas- 

 trie, and (VII) the largest of the three, which gives passage to the 

 facical nerve and certain blood vessels. Below these, near the lower 

 extremity of the exoccipital, is the Large foramen through which the 

 internal carotid artery enters the skull. 



The external auditory meatus leading into the tympanic cavity 

 occupies the usual position deep in under the squamosals, and com- 

 pared with the same opening in Crocodilus americanus no essential 

 differences are apparent. Leading hack from the tympanic eavity 

 is a canal in the quadrate through which the cartilaginous rod passes, 

 and during life is continuous with Meckel's cartilage within the 

 articular bone of the mandible. 



Viewed from the. side, the occiput above the level of the floor of the 

 foramen magnum is inclined decidedly forward up to the parietal, 

 and the part below this level inclined forward to a somewhat greater 

 extent in passing down to the lower extremity of the basisphenoid, 

 which continues below the basioccipital to meet the conjoined 



pterygoids. 



On account of the damaged condition of the brain case, the ele- 

 ments comprising it can not be differentiated, although all the impor- 

 tant foramina can be located. Taken in order from back to front they 

 are: Foramen oral] for the trigeminal nerve; the pair of foramina 

 lying beneath the pituitary fossa which furnish passage for the 

 carotid arteries; and the large anterior foramen for the exit of the 

 olfactory nerves. In nil essentials the relationships of the several 

 foramina are very similar to those found in the skull of extant 

 crocodilians. 



Tin tutli. The dental formula of Leidyosuchus sterribergii is 



2 | ■_' | 



^Y = 90. in the type-specimen we are fortunate in having four- 



— I — 1 



teen teeth in the upper and three in the lower mandible in a good state 

 of preservation, in addition to the crowns of three others found 



detached. 



The teeth /'// .situ are distributed as follows: First of the left pre- 

 maxillary; fourth, sixth, seventh (germ tooth), eighth, twelfth, 

 thirteenth, fifteenth (germ tooth), seventeenth, and eighteenth of 

 the left maxillary; fourth (germ tooth), seventh, eighth, and ninth 



