HOLLAND: THE OSTEOLOGY OF DIPLODOCUS MARSH 243 
strongly suggests to the writer that it had a function supplementary to the function 
of the true narial opening. 
The Foramina at the Junction of the Premaaxillaries and the Posterior Processes of the 
Premawillaries (Plate XXIV.).— At the point at which the premaxillaries touch the 
anterior extremities of the two long and narrow bones which Professor Marsh inter- 
prets as posterior prolongations of the premaxillaries (though these bones do not 
seem to the writer to be what Professor Marsh declares them to be) there is on 
either side of the anterior extremity of these bones a foramen approximately 3 
centimeters in length and about .75 cm. in width. These two foramina extend with 
their longer axes parallel to the line of the symphysis of the two narrow bones, and 
the outer margin of each side is apparently formed by a narrow notch in the inner 
margin of the maxillary bone. These two foramina are very distinctly shown in 
Professor Marsh’s type specimen (U. S. N. M., No. 2673). (See Plate XXIV.) 
They occupy a position which is relatively more nearly that which is held by the 
narial openings in many of the recent reptilia, and so far as the writer is able to 
judge from an examination of the skull, communicate with the narial cavity. 
The Pineal or Parietal Foramen (Plate X XVIII.).— Professor Marsh, “ Dino- 
saurs of North America,” page 175, says: “On the median line, directly over the 
cerebral cavity of the brain, the type specimen of Diplodocus has also a fonta- 
nelle in the parietals. This, however, may be merely an individual peculiarity.” 
On page 176 he says: ‘“‘There is no true pineal foramen, but in the skull here 
figured, Plate XXV., there is the small unossified tract mentioned above. In one 
specimen of Morosaurus a similar opening has been observed, but in other Saurop- 
oda the parietal bones even if thin are complete. The suture between the parietals 
and frontal bones is obliterated in the present skull, and the union is firm in all the 
specimens observed.” A very careful study of the two specimens, which were 
jointly used by Professor Marsh while prosecuting his researches, as is evidenced by 
the drawings made at the time, some of which he used in his work upon the dino- 
saurs of North America, others of which he did not use, but which have been 
kindly placed at the disposal of the writer by the authorities of the United States 
National Museum, shows that in specimen No. 1921 (U.S. N. M. Catalogue, No. 
2672) there is no evidence whatever of the existence of a pineal foramen. The 
opening in the top of the skull (see Plate X XIV.) is evidently due to artifical causes 
and has been produced either by accident, or by the use of an instrument. In the 
other specimen, No. 1922 (U.S. N. M. Catalogue, No. 2673), which is undoubtedly 
the specimen which Professor Marsh refers to as the “type,” there is a protrusion 
upward of the matrix, with which the cerebral cavity had become filled, and the 
