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488 



MONOGliAPUS OF NOltTU AMERICAN KODKNTIA. 



A group Saccomyina* un<ler a fiunily Muriila:, tvus establislied in 1848 by 

 G. R. Wuferliouse to contain all those American Rodents which have external 

 cheek-pouches, and consequently included the genera Geoiiiya and Thomomys, 

 as well as those just specified. Such comprehensive acctptation of the grouj) 

 as a family was endorsed by Baird in 1857, t and more recently by Mr. E. R. 

 Alston, t These authors agree, furthermore, in dividing the Siiccoinyidtf, as 

 understood by Waterhouse, into two subfamilies; Professor liaird's group.s 

 being Saccomyin(t-\-GeoinyincB^.8accomyi(Le, while Mr. Alston, with unnec- 

 essary§ change of nomenclature, makes Geoinyiiice-\-Heteromyin(Ez^Geomy- 

 idcE. Thus a nominal disagreement is brought about, when really these two 

 authors are at one, both in their valuation and tlieir 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 proposeil in tlio text, p. S, vol. ii, of tlio Nat. Hist. Mnnim. 

 (1848), aathe " pnivlKioual" ileHignationof agroiipof noassignid valuation, with the following doQnitioD 

 iu a foot-not*: — 



"A group of Rodents found in North, and Central America, ami in some of the West India Islands ; 

 all the spi'cios of which imsseSM cbeek-ponches, opening cxtorunlly ; (hoy have 7^ molar teeth. In some 

 the (eelb are rootless, and tiio tail is short ; tbey constitute the genus Geoniys ; in others the tail is long, 

 and the molitrs arc rooted, as in the genus Heteromys, Saccomys, and Perognathus. Dipi.doniys no doubt 

 also belongs to this section, which I provisionally form for genera which there apiwar to bo good reasons 

 thus tc unite." (See also K. Johnston's ed. of Oerbaus's Physical Athis, Table of tbeOrdeis Kodeutia and 

 Euminantia, No. 5, folio, Edinburgh, X849.) 



In his earlier papers, Waterhouse bad placed Oeomyt among true Murine forms in a " family " 

 Arvicotidai. See " Observations on the Eodentia, with a view to point out the groups, us indicated by the 

 structure of the Crania, in this order of Mammals." < Cbarlesw. Mag. N. H. viii, laiO, pp. UO-96, 184- 

 188, 274-279, 593-fiOO ; wood-cuts. (See also Ann. Mag. Nat. Hist, viil, 1841, pp. 81-«4 ; x, 1842, pp. 197- 

 803, 344-347 ; and P. Z. 8. 1^*39, pp. 172-174.) 



t Mammals of North America, p. 365 (4to, Washington, l&W). 



t On the Classification of the Order Glires. < Proo. Zoiil. 80c. Lond., Jan. 1876, pp. 01-98, pi. iv 

 (See especially pp. (.9 and 87.) A paper no student of the Rodeutia should fail to consult. 



} I cannot agree with Mr. Alston that, beoanse Fr^d. Cuvier's genus Saccomyi is donbtlcss a synonym 

 of Heteromiji Uesm., it is in consequenco necessary to derive the name of the sabfuniily from the latter, 

 and speak 'i( Huteromyiiiw 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 su h name 

 should indicate a characteristic or otherwise leading generic type. Hence, though Saeoomy is an 

 undoubted synonym, it is not necessary to discard the terms Saccomyina and Saccomyida, long established 

 and in genera! employ, as well as suggestive and pertinent. 



II Brandt, perhaps alone among late loading writers, disaimts from the views here implied. " In bis 

 recent paper on the clasaillcation of the Kodentin in Beitriigo zur nlihern Keiintniss der Sliugetblere 

 KuBslands, 1855, 188, [ho] establishes a family of Sciiiro-fpalacoidn to contain Oeomyt and Thomomy-, as 

 constituting n connecting link between the Sciiiriam and a fomlly of Spalaooidai, typified by Spalax, 

 Siphneut, Ellobiut, &c. He dissents from the views of Waterhonso in combining Oeomyt and Tkomomyt 

 into a family with Perognalhm and Dipodomyt. Peroguathut ho considers rather as a Mnroid, and coming 

 next to Cricelttt, while Dipodomyt, or rather Sfacrocolnt, is placed as the type of a sub-family MacrocoHni 

 under the Dipodoidct. I think, howi'ver, a revision of the subject, with more ample materials before him, 

 will satisfy this eminent zmdogist of the soundness of Waterbouw^'s view."— (Quoted from Baird, M. N. 

 A., pp. 3t)5-6, as pertinent to the history of the subject, and as a statement iu which I fully concur.) 



