14 Part III. — Tiventieth Annual Report 



fishes specially dealt with is over 2000, and represents 56 different 

 kinds, belonging to 37 genera. In the examination of these fishes 

 special care was taken that it should be as exhaustive as possible, 

 and the general results brought out tend to show that the food of 

 small and immature fishes of all kinds consists largely of minute 

 and young Crustacea, and that though young shell- fishes and other 

 invertebrates are also sometimes met with in the stomachs 

 examined, they are usually much less frequently observed, and 

 therefore, as a food supply for small fishes, they are not so 

 important. It is also shown that minute Crustacea form the chief 

 constituent in the food of the young of many species, which when 

 adult live mostly on other organisms. 



In the preliminary part of the paper reference is made to the 

 difficulty sometimes experienced in identifying the contents of 

 fishes' stomachs, especially if these should consist of the remains of 

 soft-bodied animals ; and in connection with this it is pointed out 

 that where the contents consist of fish remains, the earstones, if 

 present, from their peculiar form or structure may sometimes 

 be of use in assisting to identify the species to which the remains 

 belong. 



The Cod, Saithe, and Lythe. 



The paper contributed to the Report by Dr. Williamson covers 

 an investigation into the structure of these three species of the cod 

 family, and is part of a research on the specific differences of the 

 members of the group. 



A revision of the species of this family is much to be desired ; 

 and as a basis for a stable classification, and for the fixing or 

 elimination of certain doubtful species, the work detailed in the 

 present Eeport was taken up. Three forms, viz., the cod, saithe, 

 and lythe, are treated very fully. They are compared with one 

 another as to their external characters, and also as to the shape of 

 the bones which go to form the skeleton of the head. 



The various external characters which distinguish the species 

 from one another are very fully described, a series of measurements 

 being given ; while the differences and resemblances in the bones of 

 the head are compared. The paper, which is illustrated by a series 

 of plates, will, when completed, form a valuable memoir of the 

 group. 



The Parasites of Fishes. 



The study of fish parasites is intimately associated with fishery 

 investigations, and has, therefore, for the past few years had special 

 attention devoted to it. Mr. T. Scott contributes an additional 

 paper on the subject to the present Eeport. There is still consider- 

 able divergence of opinion as to whether these so-called parasites 

 are really injurious to fishes or not. Weakly fish are occasionally 

 captured, which on examination are seen to be infested with 

 parasites, but it is not generally clear whether the emaciated con- 

 dition of the fish is owing to their presence or has resulted from 

 another cause, the parasites merely taking advantage of the reduced 



