. Breviora. BRIVIORA No. 301 divided bv a spur directed internally from the united anterolophid and metalophid (Reig, 1950:1 13, fig. 2c); this suggests a method of origin of the extra lophid. is specialized as regards the progressive enlargement of the check teeth from dm j back- ward and the progressive obliquity of the lophids in the lower series. In the late Pliocene Isomyopotamus and Paramyocastor (Ameghino, 1904:252) these tendencies are less marked. An imperfect skull of Spaniomys is known (Scott. 1905:410- 411). This displays certain resemblances to Wyocastor, The ros- trum
. Breviora. BRIVIORA No. 301 divided bv a spur directed internally from the united anterolophid and metalophid (Reig, 1950:1 13, fig. 2c); this suggests a method of origin of the extra lophid. is specialized as regards the progressive enlargement of the check teeth from dm j back- ward and the progressive obliquity of the lophids in the lower series. In the late Pliocene Isomyopotamus and Paramyocastor (Ameghino, 1904:252) these tendencies are less marked. An imperfect skull of Spaniomys is known (Scott. 1905:410- 411). This displays certain resemblances to Wyocastor, The ros- trum is relatively long and its ventral border somewhat elevated above the bony palate, the tip of the upper incisor is approximately at the level of the cheek teeth, the paroccipital processes are longer and the lateral processes are freely projecting (fide Scott'). The coronoid process of the mandible is not reduced, but sueh reduc- tion may have been a late event in the group. Ameghino describes the coronoid o\ Paramyocastor as being "mucho mas larga que en. Fig. 1. Spaniomys modestm Ameghino. x 4. 15577. Dorsal view of incomplete left mandible. Princeton University No. 'The specimen (American Museum No. 9529) does not now show these last two features clearly; possibly it has suffered some damage since Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Harvard University. Museum of Comparative Zoology. Cambridge, Mass. , Museum of Comparative Zoology, Harvard University
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