22 BULLETIN OF THE BUREAU OF FISHERIES. 



recommended that a simplified card catalogue be maintained at the laboratory in the 

 future for the reception of further data as they accumulate. Such a system, if properly 

 cared for, would furnish a receptacle for fragmentary notes and records which otherwise 

 would be lost. 



(5) For occasional or random observations by local observers a provisional mode of 

 entry was adopted and another type of card, uniform in size with the last, was printed for 

 the purpose. This card, although likewise capable of improvement, proved to be 

 extremely useful. 



We trust that the following explanations and admissions will not be construed as an 

 apology for the results herein offered. Without such a frank confession of the limita- 

 tions of our work and of the difficulties encountered, we should expose ourselves to the 

 criticism of making pretensions which have not been reahzed. It is only fair to our- 

 selves that we should disarm such criticism as is based upon the assumption that we have 

 enjoyed greater facilities and opportunities than was actually the case. Moreover, 

 fairness and scientific accuracy demand that there be a clear separation between those 

 of our results which we regard as clearly established and those which are to be 

 regarded as merely probable. The reader's confidence in what we trust are really sub- 

 stantial and valuable acquisitions should not be shaken by the discovery of various 

 undeniable sources of error and uncertainty. 



The fact must be emphasized at the outset that the work of the Survey, with a few 

 important exceptions, was restricted to the summer months. The vessels employed 

 were commonly available not earlier than July i and not later than September i . This 

 is likewise the period during which those immediately in charge of the dredging opera- 

 tions were free for work of this sort. Without exception, the biological staff was con- 

 stituted by university or college men — instructors or graduate students — who were 

 busily occupied in their teaching or their studies for about nine months of the year. 



From these circumstances there has resulted a two-fold limitation of the work. 

 First, with respect to the dredging results, we can only offer a record of midsummer 

 conditions; second, it is obvious that neither as much work nor as high a degree of prepa- 

 ration can be expected of a staff thus constituted as from one composed of naturalists 

 permanently engaged in pursuits of this sort. We must confess in all frankness that we 

 found it necessary in large degree to develop our own methods through experience, 

 and that the earlier dredging operations are to be regarded as in large measure practice 

 work. This fact, however, has been recognized by the authors throughout, and for this 

 reason the field of these earlier labors was explored later with far greater care and 

 thoroughness. 



Due allowance must likewise be made for the fact that those of us who listed and 

 sorted the dredging material in the field and in the laboratory make no pretensions to 

 being universal naturalists having a "speaking acquaintance" with practically every 

 species of animal and plant likely to be encountered by us. We will add the further 

 admission that on many occasions no one of the party thus employed was a recognized 

 authority upon a single group of animals, considered from the standpoint of taxonomy. 

 But this state of affairs has resulted, we believe, almost wholly in errors of omission, 

 many of which have been subsequently rectified. At the outset we familiarized our- 

 selves with those species which were readily recognizable, and endeavored to learn in 

 just what cases confusion was possible and special care necessary. The advice of 



