1022 MR, OLDFIELD THOMAS ON THE (Dec. 15, 
100. Tachyoryctes, Riipp.’ 
[Chrysomys, Gray, List Mamm. B. M. 
p- 150 (1843).] 
B. SPaALAcIn». 
101. Spalax, Giild. 
Noy. Comm. Petrop. xiv. art. i. p. 409 
(1770). 
VIII. Geomyide. 
102. Geomys*, Raf. 
Am. Month. Mag. ii. p. 45 (1817). 
103. Thomomys, Wied. 
N. Act. Leop. xix. pt. i. p. 883 (1839). 
IX. Heteromyide. 
A, DrropoMyIn2. 
104. Dipodomys, Gray. 
Ann. Mag. N. H. vii. p. 521 (1841). 
105. Perodipus, Fitz. 
SB. Ak. Wien, lvi. p. 126 (1867). 
106. Microdipodops, Merr. 
N. Am. Faun. no. 5, p. 115 (1891). 
B. Heteromyin 2. 
107. Perognathus*, Wied. 
N. Act. Ac. Leopold. xix. pt. i. p. 369 
(1839). 
108. Heteromys, Desm. 
Mamm. i. p. 313 (1822). 
service to me. Some important observations on the relations of the Rhizo- 
myine to the Mascarene Sigmodontes are given by Dr. Forsyth Major, supra 
. 979. 
Bos The African Bamboo-Rats, given provisionally the above name by Riippell, 
were rightly distinguished by Gray, but the distinction has been generally lost 
sight of tillnow. The molars are of quite a different structure in the two 
roups. ° 
z Tes unfortunate that Riippell’s name has to be used for this genus, as he 
deliberately rejected the idea of its being distinct (from Bathyergus!), and yet 
proposed the name in case other workers thought it valid. It is to be hoped 
that there are few people now left who would do a thing like this, by which an 
author attempts to secure priority for his own name at the expense of somebody 
else’s work, while he fears to take the responsibility of describing a new form 
for himself. Some naturalists even refuse to accept such names, and I wish I 
could feel justified in doing the same. 
2 Dr. Merriam has divided the old genus Geomys into eight genera, but for 
the purposes of the present paper these may be most conveniently treated as of 
subgeneric rather than generic rank, sound as their basis as natural groups no 
doubt is. 
3 Dr. Coues (Mon. N. Am. Rod. p. 495, 1877) speaks of separate subfamilies 
for Perognathus and Hetercmys; but they seem really to be very closely allied 
to each other, especially if some of the larger species of the former, such as 
P. paradoxus, be compared with members of the H. allent group of Heteromys. 
