AKCJULID.-E OF THE WOODS HOLE REGION. 119 



gate upon the remainder and thereby increase their mischievous influence. Actual 

 observations of the number of parasites present and their influence upon migrating 

 iish are exceedingly meager and we have to be satisfied with a few crumbs of 

 information, but it is more than evident that here is a field of inquiry which 

 promises large returns for the future. 



Another change that is always more unfavorable to the fish than to the parasite 

 is the increase of temperature in our fresh-water ponds during the summer season. 

 If the pond happens to be shallow there may tie a sufficient rise to produce fatal results, 

 along with the accompanying increase of Arguli. Several such instances are upon 

 record. Mr. F. L. Washburn (American Naturalist, XX. p. 896) records the death of 

 thousands of fish during the summer season for several years at Lake Mille Lac in 

 .Minnesota. This lake is quite shallow, and the water becomes correspondingly warm 

 dining July and August, at which time the fish die in such numbers that the beach is 

 strewn for miles with their dead bodies. Washburn says: 



The evident cause of death is the presence of an external parasite, one of the Siphonostomata, 

 which we found swarming on head, operculum, and belly. These parasites are. translucent, disgusting 

 looking creatures about the size and shape of a wood-tick, though many an- larger, the abdomen 

 furnished with an umbrella-like disk, which apparently assists them in clinging to their slippery 

 heists. 



This is far from being a scientific description, but there is little doubt that a 

 species of ArguVm is referred to, especially when the kinds of fishes mentioned and 

 the attendant circumstances are considered. The parasites had gathered upon the back 

 of the tish, choosing most frequently a spot near the head, but often there were large 

 patches upon the sides and belly. Washburn enumerates the following species among 

 the dead: The wall-eyed pike {Stizostedion vitreum) was by far the most abundant: 

 after this came yellow perch {Percafiavescens), rock bass {Ambloplites rwpestris), black 

 bass {Micropterus), bull-head {Aineiurus), crappy {Pomoxis annularis), calico bass 

 {Pomoxis sparoides), whitefish {Argyrosomus artedi), ling {Lota maculosa), dogfish 

 (Am/11 ciil ni), pike {Esox I in-; us), and large suckers. 



In the succeeding volume of the Naturalist (XXI, p. 188), Prof. K. Ramsay 

 Wright mentions a corresponding mortality of an undetermined species of ( 'oregowus 

 in Lake of the Woods as reported to him by Mr. A. C. Lawson, of the geological 

 survey of Canada. The death in this case was due almost entirely to a species of 

 ArguVus of which fortunately specimens were secured, and the author has had the 

 pleasure of examining these recently. They prove to be Argulus sti;:<>s/, thii Kellicott, 

 and thus add a new host for that species, besides confirming Kellicott's statement in 

 regard to the original host, the blue pike {Stizostedion vitn »/»). This Argidus was first 

 obtained from pike taken in the Niagara River at Buffalo, and Kellicott states that he 

 has verified the reports of local fishermen to the effect that when the water is warm 

 during midsummer this pike "gets too lazy to take food; that it then gets poor and. 

 through its inertness, becomes infested with lice." They are usually found upon the 

 top of the fish's head, often "huddled together in heaps, so the knife may remove a 

 number at once.''' 



It seems almost certain that some, at least, of the parasites found by Washburn 

 must have been A. stizostethii, though there may have been other species also. 

 Washburn recognizes the fact that the warm water played an important part in 



