INTRODUCTION. 



§ 1. Remarks upon the Distinction of Species and upon sub- 

 family DIVISIONS. 



The writer is fully aware that the time is not yet ripe for a final 

 review of the family Delphinidcc. The work now accomplished must 

 be regarded as provisional and subject to revision in the future. 



iSoine of the great hindrances to the study of the dolphius^the scarcity 

 of material, the iguaranceof the limits of specific variation, and the like — 

 have already been pointed out by Professor Flower, and it is not neces- 

 sary that I should d^vell upon these points. One other difficulty which 

 is encountered by every student of the Cetacea arises from the incom- 

 pleteness of the descriptions of species. In numerous cases only the 

 external appearance of the species is described (and this from a single 

 individual), the description being accompanied by one or two measure- 

 ments, such as the total length or the greatest girth. In other instances, 

 equally numerous, species are described from a single skull. It is evi- 

 dent that if this condition of affairs affected the entire famil}^ tliere 

 would be two series of species: First, those founded on external appear- 

 ance alone; and, se(!ond, those founded on osteological characters alone. 

 Such a condition of affairs does, indeed, to a large extent prevail and 

 has proved the cause of much confusion. 



A naturalist can, however, scarcely be regarded as deserving censure 

 for having described the skeleton of a species tlie external appearance 

 of which is unknown to him. If the description is full and accurate 

 it must be accepted, and cetologists must be content to wait patiently 

 until the acquisitions of new specimens make a comi)lete description 

 possible. 



Some writers, however, seeking to avoid the difficulty arising from 

 this multiplication of names, have produced confusion in another way. 

 Having come into' the possession of fresh specimens, or of skeletons, 

 accompanied by collectors' notes on the external appearance, they have 

 identified the former witli specie? insufficiently describ3d by previous 

 writers from external ch iracters alonr^, and, without giving figures or 

 measurements of the exterior, h ive proce-ede I to describe tlie skeleton. 

 It is evident that a student approaching the subject at a later date has 



