276 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



From the pylorus was obtained a single specimen of Tetrarhynchus robuslus (Cestode Parasites of 

 Fishes) p. 452. 



One of the larger specimens of K. agile measured 95 mm. in length. It was noticed that these 

 specimens contracted very greatly when placed in the killing fluid (Long's aceto-picro- mercuric 

 lluid), especially the mature and maturing proglottid.es, some of the latter contracting to one-fourth 

 their length. Specimens were then stretched on the bottom of a glass dish and allowed to lie there a 

 short time until they were fastened by their own mucilage. They did not then contract when the 

 killing llnid was placed on them. 



11 a. Catostomus commersonii, Common Sucker. 



August 26, I received a specimen of sucker and a bottle containing a large number of parasitic 

 copepods, which were sent to me by Dr. H. M. Smith. Along with the specimens was a letter from J. W. 

 Titcomb, superintendent of the Fish Commission station at St. Johusbury, Vt. The fish and par- 

 asites had been collected by I. W. Parks, Montpelier, Vt. Mr. Titcomb wrote : 



Through the courtesy of I. W. Parks, veterinary surgeon at Montpelier, Yt., I have obtained a 

 lot of specimens of the parasite which infested the river there this summer and a sucker which had 

 been attacked by them. It will be noticed that one of the pectoral tins is quite badly eaten and a 

 spot on the fish below it. These parasites usually attack the pectoral fins first. They are sometimes 

 found on the eyes of the fish and apparently stand on their heads in working into the fish. 



These parasites belong to the genus Argulus, probably A. catostomi Dana and Herrick. The 

 abraded place on the side of the fish was examined and the tissues were found to be penetrated by the 

 hyphte of some fungus, presumably a species of Saprolegnia. Since the month parts of Argulus are 

 fitted for piercing and sucking, and not for biting, it seems rather hard to account for the frayed and 

 tattered condition of one of the pectoral fins of this fish. Because of the presence of the fungus noted 

 above, I stated in my letter to Dr. Smith relative to this case that these parasites may not have been 

 wholly to blame for the damage, although the trouble might have been started by them. 



Later I received a letter from Mr. Parks, dated September 20, in which he gives an interesting 

 account of his observations on the effect of these parasites 011 trout and suckers. The following 

 extracts, give the substance of his observations. After speaking of a fish which had no marks of any 

 kind upon it when he first saw it, which was swimming in shallow and clear water, he proceeds: 



First the fish swam along in the usual manner feeding, but soon became uneasy, this increasing 

 until it seemed to become frenzied. This stage does not last more than 30 minutes, however and 

 then it commenced to turn upon its back and became comatose and soon died. To make 



sure the parasite was the cause of death I obtained trout and suckers from an adjacent stream, and 

 after placing the sucker in a tank of fresh water I dropped in about fifty of the parasites, which at 

 once attacked the fish. While they were upon the sucker I placed three trout in also. In 55 minutes 

 I noticed signs of frenzy and in 75 minutes coma, and in 90 minutes the first trout was dead, and upon 

 examination I found the left pectoral fin completely stripped, the right eye destroyed, a spot near the 

 tail stripped of the scales the size of a ten-cent piece. I find that suckers can live longer than trout, 

 also the parasites will go from a sucker to trout. 



The ArguUdce, according to Clans (Zeitschrift fur Wissenschaft, ZooL, xxv, 3, 1875, p. 277), live 

 on very different sorts offish, and chiefly on the plasma of the blood to which they obtain access by 

 means of modified mandibles and maxilhe which are transformed into a piercing and sucking organ. 



12. Aiiguilla chrysypa, Common Eel. 



(1) July 25; one; stomach empty. 



Cestodes: Cysts containing larva', on mesentery, several, Rhynchobothrium imparispine Lt. (Ces- 

 tode Parasites of Fishes, p. 450.) 



Nematodes; one eucapsuled on liver, immature; not yet identified. There was an inflamed patch 

 on the stomach wall and on the intestine, evidently caused by a wound on the side. 



(2) AugustS; one; partly digested fish in stomach. 



One hyaline cyst on viscera, containing a Rhyuchobothrium larva. When released it remained 

 attached to the blastocyst. 



(3) August 29; one; stomach empty. 



The only entozoou found was a single immature cestode larva of the type which I have found 

 in the alimentary canals of a variety of fish; small, with two red spots on the neck. (Larval Cestode 

 Parasites of Fishes, pp. 789-792, pi. LXI, figs. 4-15.) The stomach and intestine were washed and the 

 contents looked over very carefully with the above meager result. The specimen had been in an 

 aquarium for a few days. 



