VIII INTRODUCTION. 



oiskoleton, or .specimen preserved in alcohol. (8) Age and sex of .speci- 

 men; omission of the sex indicates that it is not known. (4) Date when 

 collected ; omission of this date indicates that it is not known. (5) Name 

 of person l)y whom collected, or from whom received, or from whom 

 purchased, if collector is not known. (G) Oiiginal number of speci- 

 men, usually the number in the collector's field cataloj^ue. In the case 

 of certain of the Biological Survey specimens, the original luunber is 

 followed by the letter x, which indicates that the specimen is recorded 

 in the " X Catalogue '" of the Biological Survey, a l)ook in which is 

 catalogued material received from miscellaneous sources— that is. 

 specimens purchased, acquired by exchange, oi" received from or col- 

 lected by persons wdio aie not on the regular staff of the Biological 

 Surve3\ (7) Date when specimen was catalogued, except in the case of 

 Biological Survey specimens, most of which were catalogued shortly 

 after the date of collection. In the case of many of the National 

 Museum specimens, the date when catalogued gives the only clue as 

 to the probable time when collected. 



The condition of thf specimen at the pr(\^ent time is then brieHy 

 stated." 



Finally, the rea.sons arc given for considering any specimen a type, 

 imless it has been clearly designated as a type by mimber l)y the author 

 in the original description. In many early descriptions it is difKcult 

 to determine whether any individual specimen has formed the principal 

 basis of the description. In cases where no type was indicated })y the 

 authoi-, preference has been given to the sj)ecimens which have been 

 figured, or to those which seem to be more minutely described, or 

 measured, than others of the original series. The views of subsequent 

 writers also have been considered in the selection f)f the type. In 

 some cases it was necessary to choose a numbei' of specimens as cotypes 

 of a species. In a few ca.ses the evidence for consideiing specimens 

 types is very unsatisfactory. However, even if not types in the 

 present meaning of the word, they are at least old. original specimens 

 of nuich histoi'ic value. These difficulties relate mainly to older 

 specimens in tho collection contained in the Division of Mannnals. 



Since a single type-specimen sometimes has more than one catalogue 

 number, a few words about cataloguing specimens seem desiial)le. Two 

 .sy.stems have been used: First, a ''double entry" .s3'.stem, in which all 

 the skulls were cntei'ed in one catalogue, and all skins and alcoholics 

 in another; and in the usual ca.se of a single individual lepresented by 

 both skin and skull, cross references are given in each catalogue. The 

 number of a specimen is indicated by a fraction; thus, No. 2 J" 5 on a 



"A few of the type-spccinicns are among material that has been lent to si)ecialist,>.» 

 for study and have been deserilied while in their hand.«. Some ot tliese have not 

 yet been returned and it is ol)vi(>usly in)i>ossil)le to make any statement as to their 

 condition, but on the whole it is presumed to be good. 



