69 INDEX GENERUM MAMMALIUM. 

'ategories—those derived from the name of the collector of the species 
on which the genus was based, like /ruzjn£a, Carloameghinia, and Nel- 
sonia, and those named in compliment to some distinguished person, as 
Garzonia, tor Don Eleazar Garzon, governor of the province of Cor- 
doba, Argentina; Capaccinius, for Monsignor Francesco Capaccini, 
under secretary of state of Rome, and Romerolagus, for Don Matias 
Romero, formerly Mexican minister to the United States. In the first 
group the application is obvious, provided the person is stated as the 
collector; in the second group, however, the application 1s by no 
means evident, and without explanation is often very obscure. 
(5) Geological names.—Names indicative of age, or ‘geological 
names,’ are frequently employed in paleontology to show the age of 
the deposits in which the animals were found. The most frequent are 
compounds of eo-, ;nzo-, and plio-; thus Lopithecus, Miopithecus, and 
Pliopithecus represent apes from the Eocene, Miocene, and Pliocene. 
Similarly a few compounds have been made from c7z;- and ceno-; 
thus Cimolestes, Cimolodon, and Cimolomys indicate mammals from 
the Cretaceous (chalk); and Cenobasileus, Cenopithecus, and Cenothe- 
rium, mammals from recent or Quaternary beds.“ The prefixes hyper- 
(above), Znfra- (below), proto- (first), pro- (before), ;ieso- (middle), and 
post- (after), are also employed to represent relative age, as /7yper- 
Érag ulus, Infrapithe CUS, Protohippus, Promeles, Mesohippus, and 
Postpithecus. Occasionally names have been suggested by the char- 
acter of the beds in which the fossils were discovered; thus Anthraco- 
therium is à. genus from the anthracite or lignite beds of Tuscany, 
Argillothevium one from the London clay, Chalicotherium one from 
the gravel beds of Eppelsheim, and S7derotheriwm one from the iron 
ore deposits near Mésskirch, Baden. 
(6) Descriptive names.—Names indicative of size, form, color, and 
resemblance may be found in almost endless variety, and usually present 
few difficulties. Size is indicated in all gradations from the huge Jege- 
therium to the pygmy JVannosciurus, but though the meaning of such 
names may be obvious, yet they convey no idea of absolute size to show 
that their selection is especially appropriate. Thus while J/egamys 
plainly refers to a large rodent, it does not show that the mammal thus 
named was supposed to have been as large as an ox; and while J/cro- 
cebus is a small lemur, the fact that some species of the genus are only 
5 inches in length (exclusive of the tail) is not shown. Similarly 
‘small shrew’ does not suggest the fact that J/crosorex is in reality 
one of the smallest mammals, with a total length of only 33 inches. 
Form is expressed in all gradations from fat (Steatomys) to thin 
(Stenobalena); from thick (Pachysoma) to slender (Leptomys); from 
short (Brachyiherium) to long (Dolichother‘um). Color and markings 
play a comparatively unimportant part in the formation of generic 
names, but are used as a basis imn a few cases. References to color in 
“ Cienolestes, however, has been applied to a living mammal, 
