488 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 
A group Saccomyina,* under a family Muride, was established in 1848 by 
G. R. Waterhouse to contain all those American Rodents which have external 
cheek-pouches, and consequently included the genera Geomys and Thomomys, 
as well as those just specified. Such comprehensive acceptation of the group 
as a family was endorsed by Baird in 1857, and more recently by Mr. I. R. 
Alston.t These authors agree, furthermore, in dividing the Saccomyide, as 
understood by Waterhouse, into two subfamilies; Professor Baird’s groups 
being Saccomyine+ Geomyine = Saccomyidz, while Mr. Alston, with unnec- 
essary § change of nomenclature, makes Geomying + Heteromyine = Geomy- 
ide. ‘Thus a nominal disagreement is brought about, when really these two 
authors are at one, both in their valuation and their definition of the groups in 
question. || 
I accept the groups as originally indicated by Waterhouse, and as limited 
by Baird and Alston, but I differ in my valuation of them, considering that 
*“ Saccomyina”—a name informally proposed 10 the text, p. 8, vol. ii, of the Nat. Hist. Mamm. 
(1848), as the “ provisional” designation of a group of no assigned valuation, with the following definition 
in a foot-note: — 
“A group of Rodents found in North, and Central America, and in some of the West India Islands ; 
all the species of which possess cheek-pouches, opening exterually ; they have 5 molar teeth. In some 
the teeth are rootless, and the tail is short ; they constitute the genus Geomys; in others the tail is long, 
and the molars are rooted, as in the genus Heteromys, Saccomys, and Perognathus. Dipodomys no doubt 
also belongs to this section, which I provisionally form for genera which there appear to be good reasons 
thus to unite.” (See also K. Johnston’s ed. of Berhaus’s Physical Atlas, Table of the Orders Rodentia and 
Ruminantia, No. 5, folio, Edinburgh, 1849.) 
In his earlier papers, Waterhouse had placed Geomys among true Murine forms in a “ family” 
Arvicolide. See “ Observations on the Rodentia, with a view to point out the groups, as indicated by the 
structure of the Crania, in this order of Mammals.” < Charlesw. Mag. N. Il. viii, 1839, pp. 90-96, 184— 
188, 274-279, 593-600 ; wood-euts. (See also Apn. Mag. Nat. Hist. viii, 1841, pp. 81-84; x, 1842, pp. 197— 
203, 344-347; and P. Z. S. 1839, pp. 172-174.) 
+t Mammals of North America, p. 365 (4to, Washington, 1857). 
t On the Classification of the Order Glires. < Proc. Zodl. Soc. Lond., Jan. 1876, pp. 61-98, pl. iv. 
(See especially pp. (9 and 87.) A paper no student of the Rodentia should fail to consult. 
§ I cannot agree with Mr. Alston that, because Fréd. Cuvier’s genus Saccomys is doubtless a synonym 
of Heteromys Desm., it is in consequence necessary to derive the name of the subfamily from the latter, 
and speak of Heteromyina instead of Saccomyina. It is always admissible to derive the name of a sub- 
family or family from any one of its component genera, though, of course, desirable that such namo 
should indicate a characteristic or otherwise leading generic type. Hence, though Saccomys is an 
undoubted synonym, it isnot necessary to discard the terms Saccomyinaw and Saccomyid@, long established 
and in general employ, as well as suggestive and pertinent. 
|| Brandt, perhaps alone among late leading writers, dissents from the views here implied. “ In his 
recent paper on the classification of the Rodentia in Beitriige zur niihern Kenntniss der Siiugethiero 
Russlands, 1855, 188, [he] establishes a family of Sciuro-spalacoides to contain Geomys and Thomomys, as 
constituting a connecting link between the Sciuriaw and a family of Spalacoides, typified by Spalaa, 
Siphneus, Ellobius, &c. He dissents from the views of Waterhouse in combining Geomys and Thomomys 
into a family with Perognathus and Dipodomys. Perognathus he considers rather as a Muroid, and coming 
next to Cricetus, while Dipodomys, or rather Macrocolus,is placed as the type of a sub-family Macrocolini 
under the Dipodoides. I think, however, a revision of the subject, with more ample materials before him, 
will satisfy this eminent zoologist of the soundness of Waterhouse’s view.”—(Quoted from Baird, M. N. 
A., pp. 365-6, as pertinent to the history of the subject, and as a statement in which I fully concur.) 
