PELAGE.--It was found advisable to use a standardized nomenclature
for hairs. The names here proposed are a choice of those used in
the literature, with the suffix "_form_" as an element of
uniformity. I feel that it would be advantageous if everyone
adopted a similar universal system in mammalogy.
The names listed below are used as nouns and are considered as
English versions which could easily be adapted to different
languages. These names may be complemented with adjectives as
needed. Examples are lanceolate aristiforms, spinous aristiforms,
and woolly setiforms.
_Aristiforms:_ The most conspicuously developed hairs in a
three-layered pelage or the corresponding hairs in a simpler
pelage. Names previously used for these hairs are: guard hair,
leithaar and jarre.
_Setiforms:_ Common to all species and most numerous throughout the
pelage; second in conspicuousness, being the dominant hairs in the
middle layer. Synonyms are: over hairs, grannenhaare and soies.
_Villiforms:_ The smallest hairs in the three-layered pelage.
Synonyms are: underfur, wollhaar and duvet.
_Vibrissiforms:_ The vibrissae proper, or any typically sensory
hair.
TEETH.--The tritubercular nomenclature was abandoned because of
overwhelming difficulties; more research on the Hystricomorpha is
certainly needed before the tritubercular nomenclature can be
applied with confidence. The following names are used for features
of the molariform teeth:
_Main fold:_ The inner or lingual fold in the upper molariform
teeth and outer or labial fold in the lower molariform teeth.
_Counterfold:_ Any outer or labial fold in the upper or any inner
or lingual fold in the lower molariform teeth.
For incisors Thomas (1921:141) is followed: _opisthodont_,
_orthodont_ and _proodont_ depending on the angle between the
exposed part of incisors and the ventral surface of the rostrum.
The capital letters P and M designate premolars and molars,
respectively, of the upper jaws; lower case letters p and m
designate corresponding teeth in the lower jaws.
MEASUREMENTS.--Measurements of skins were used only when provided
by the collector. The length of the hind-foot is intended to be
always _cum unguis_, but in a few instances it is impossible to be
sure whether the collector included the nail. Length of tail was
used only when the tail seemed not to be mutilated. Ear
measurements taken by collectors are scarce. In spite of the
apparent usefulness of length of ear, it was found to be
inadvisable to take the measurement on the dry skins.
The following measurements of the skull are used in the tables:
_Greatest length:_ From the anteriormost part of the nasals to the
posteriormost part of the supraoccipital.
_Condylo-incisive length:_ From the anterior face of one incisor,
at the alveolus, to the posteriormost part of the exoccipital
condyle of the same side.
_Zygomatic breadth:_ Maximum distance across zygomata in a plane
perpendicular to longitudinal axis of the skull.
_Length of nasals:_ Maximum length of one or both, whichever is
the greater.
_Interorbital constriction:_ Least width between the orbits on top
of the skull.
_Palatilar length:_ From the posterior face of an incisor, at the
alveolus, to the nearest part of the posterior edge of the
palatine bone.
_Crown length of cheekteeth:_ From the anterior border of P4 to
the posterior border of M3.
In the accounts of species, measurements of aristiforms and
setiforms are used. The hairs measured were taken from the
middorsal region and outer thighs, and the measurements are means.
All specimens of which measurements are here recorded, as for
example in the tables, are fully adult; each specimen shows some
wear on each of the four upper molariform teeth unless otherwise
indicated.
Capitalized color terms are after Ridgway "Color Standards and
Color Nomenclature," Washington, D. C., U. S. A., 1912. One
setiform was taken from the animal and placed over the rectangles
in Ridgway's charts and the examination made under a microscope
with low (×7) magnification and natural light. This method was
found to give the most satisfactory results.
The following abbreviations are used for names of institutions:
AMNH--American Museum of Natural History.
CNHM--Chicago Natural History Museum.
DZ--Departamento de Zoologia da Secretaria de Agricultura, São
Paulo, Brazil.
MCZ--Museum of Comparative Zoology at Harvard College.
MN--Museu Nacional, Brazil.
MZ--Museum of Zoology, University of Michigan.
SEPFA--Serviço de Estudos e Pesquisas sobre a Febre Amarela, Brazil.
USNM--United States National Museum.
UZM--Universitets Zoologiske Museum, Copenhagen.