THE AQUARIUM BULLETIN 



33 



Hints on the Study of Fishes 



By Dr. R. W. Shufeldt, C.M.Z.S. 

 Washington, D. C. 



(Continued from September issue) 

 Both cycloid and ctenoid scales 

 may occur on the same fish. The 

 study of the scales of fishes is a 

 large subject, and it cannot be well 

 entered upon further in this place. 



In most fish the lateral line ( /. /., 

 Fig 1 ) runs along the side of the body, 

 from the head to the tail. Some fish 

 have several such lines, occupying 

 other parts of the body, and running 

 in different directions. However, the 

 one marked /. /. in Figure 1 is the line 

 usually so considered. Its scales are 

 perforated, and the duct at the base 

 of any one of them is simple. Some- 

 times this row of scales are larger 

 than others on the body, rarely 

 smaller, and they may present other 

 interesting modifications. They are 

 abundantly supplied with nerves, and 

 the function of the structure as a 

 whole is the excretion of a mucous, 

 which is very noticeable upon hand- 



By following such a line of research 

 in a very few years, it will be seen 

 that the Note-book, with its illustra- 

 tions, will form a very valuable con- 

 tribution to the biology of many of 

 our fishes — a subject that, compara- 

 tively speaking, has received but 

 scant attention in this country. 



As to a study of the skeleton in 

 fishes, the subject is one of enormous 

 extent ; and, while we have a knowl- 

 edge of this subject as applied to 

 many species, including a few United 

 States forms, we are a very, very long 

 ways from the point when we can say 

 that we have a comprehensive ac- 

 quaintance with ichthyic osteology. 

 There are simply thousands of dif- 

 ferent kinds of fish in the world of 

 which we have no knowledge what- 

 ever of their skeletons, to say iiot a 

 word as to the balance of their 

 anatomy. Indeed, it may truthfully 

 be said — if we include the deep-sea 



ling many species of fish when first | groups — that there are thousands 



upon thousands of living fishes, the 

 structure of which we know nothing 

 whatever about. Many of these have 

 special organs of the greatest possible 

 interest, of which we know nothing. 

 Unfortunately, some of our natural- 

 ists in high places are of the opinion 

 that they have fulfilled their duty 

 when they have "received a fish ; 

 identified it ; put it in a receptacle con- 

 taining a preservative, and placed it 

 in the collection," where it may not 

 be examined for the next ten years ! 

 There is not as much encourage- 

 ment along these lines as there should 

 be, as I know from long and personal 

 experience. For example, eight or 

 nine years ago I was permitted, by Dr. 



removed from the water, and often 

 for a time thereafter. In some fishes 

 the scales of the lateral line are the 

 only ones to be found anywhere on 

 the body of the fish so characterized ; 

 and for the purposes of classification, 

 it is the scales in this line that are 

 counted, the number varying in var- 

 ious species, genera, families, and so 

 on. 



Among the internal organs and 

 structures, notes may be made on 

 those of special sense, as the eye ; 

 organ of hearing; the tongue, and 

 others. Attention should be paid to 

 the szvim-bl adder and its morphology, 

 while the digestive apparatus should 

 also come in for its share of study. 



