INTRODUCTION. 



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

 family DIVISIONS. 



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

 review of the family Del2>hinidcc. The work now accomplished must 

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



Some of the great hindrances to the study of the dolphins — the scarcity 

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

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

 sary that I should dwell upon these points. Oue other difficulty which 

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

 ])leteness 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 af^iirs affected the entire family there 

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

 ance alone; and, second, 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 cejisure 

 for having described the skeleton of a species the 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 

 nntil the acquisitions of new specimens make a complete 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 forinsr with specie? insuffiaiently describ:Ml b^' previous 

 writers from external chiracters a1on;% anil, without giving fli:^(ires or 

 measurements of the estei'ior, h ive proceed^vl to describe the sknleton. 

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



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