SEA-FISHERIES LABORATORY. 189 



the parasites now known to be Copepods were not at 

 first recognised as Crustacea, chiefly because of the diffi- 

 culty of making out the true characters and the absence 

 of knowledge as to the life-histories. There was much 

 difference of opinion even as to which were really the 

 anterior and posterior extremities of these animals, due 

 to the fact that the posteriorly placed ovisacs of the then 

 known forms are cylindrical tubes which were by some 

 supposed to be the antennules, and therefore that end 

 was called the anterior. Hence many of the drawings of 

 the earlier authors represent the animals standing on their 

 heads. 



Baird's kk British Entomostraca," published by the 

 Ray Society in 1850, marks an important epoch in our 

 knowledge. This author gives an interesting historical 

 account of the group, brings together all that was pre- 

 viously known, and gives a very full account, with 

 excellent figures, of all the British species known at 

 that time, and although some of these are inaccurate in 

 detail, or have been added to by more recent investiga- 

 tions, still Baird's monograph is indispensable to any one 

 working at the subject. Since 1850 comparatively little 

 has been done in this country to increase our knowledge 

 regarding the distribution or habits of these crustaceans. 

 Within the past few years, however, the study has revived 

 and some important papers, mainly speciographic, have 

 been published. 



The latest classification of the Copepod fish parasites 

 arranges them under seven families, as follows : — Ergasi- 



LIDM, CALIGID^, DlCHELESTLD^, PhILICHTHYIME, LeRNjEID^, 



Chondracanthid^e, and LERNiEOPODiDiE. With the excep- 

 tion of the Philichthyid^;, all these families have 

 representatives living on fishes found in the seas around 

 our coasts. 



