59 



The Pygidiidae. 



Carl H. Eigenmann, Indiana University. 



There is a widespread belief in parts of South America that a fibh 

 called Candiru has the vicious habit of entering the urethra of bathers. 

 Its opercle and interopercle bear retrorse spines that are erectile. The 

 fish, therefore, cannot be v\^ithdrawn. An operation, if not amputation, is 

 necessary to get rid of the pest, and if it has penetrated to the bladder it 

 causes death. This story has been told many different travelers. Some 

 have rejected it as beyond belief, others have added to the marvelous, 

 while still others have tried to identify the fish. The result of the latter 

 attempt has been ludicrous at times, inasmuch as the identification would 

 require the reverse of the well recognized principle of logic that the 

 greater cannot enter the lesser. Some of the Candirus reach a consid- 

 erable size, a length of at least a foot and a thickness of at least two 

 inches. We will return to the Candirus. 



I have finished a monograph of the family of fishes, the Pygidiidae, 

 of which the smaller Candirus are members, and I want to give a brief 

 account of the difi"erent types of fishes that are included in this family. 

 Other species of the family have well authenticated habits as remarkable 

 as those of the Candiru, and I am fig-uring all the species I can get. 



I find that there are nearly a hundred well defined species of the 

 Pygidiidae. Many of these are very rare. Forty-four are known from 

 the types only, several have been recorded from but two localities. The 

 types are widely scattered in the museums of North America, South 

 America, and Europe. At one time or another I have examined prac- 

 tically all of the specimens in American museums, and have myself dis- 

 covered nine of the nineteen genera, and forty-three of the ninety-seven 

 species. Eight or ten of the types are in Vienna, two are in Berlin, 

 twelve in Paris, eleven in London, one in Torino, two probably in Mu- 

 nich, one in Leipzig, two in Copenhagen, one in Berne, three presumably 

 in Santiago, Chile, three in Buenos Aires, three in Rio de Janeiro, two in 

 Cordoba, Argentine, one in the Field Museum, two in the Philadelphia 



* Contribution from the Zoological Laboratory of Indiana University, No. 163. 



