S8 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



was vegetating and infesting the skin of the fish. Microscopic exami- 

 nation, however, soon showed that what Avas at first sight suspected to 

 be a fungus was really an animal parasite which had bored its way from 

 without into the skin of its host. 



Upon consulting Dr. T, H. Bean, the obliging Curator of the Depart- 

 ment of Fishes in the National Museum, he informed me that he thought 

 there were in the collection a lot of si)ecimens from farther north, of the 

 same species, infested in a similar way. Dr. Beau kindly obtained two 

 jars of these specimens for me, and also sup^ilied a copy of the Museum, 

 record pretaining to them as follows: 



N. M. No. 32354. Arichat, Cape Breton, 1882. W. A. Stearns. 

 N. M. No. 32355. Arichat, Cape Breton, 1882. W. A. Stearns. 



Examination revealed the fact that these specimens were infested in 

 precisely the same way as the one from Wood's Holl. Every part of the 

 surface of the skin was found to be raised into small rounded papules 

 or prominences of a blackish blue color, which it was found were caused 

 by thick-walled cysts embedded in the skin, into the vicinity of which 

 pigment cells had migrated or developed de novo. In all of the speci- 

 mens the cornea was more or less infested by these cysts, which were 

 imbedded in its substance, and, as in other parts of the skin, surrounded 

 by opaque pigment cells, which in this situation would, of course, seri- 

 ously impair vision, the cysts encircled with pigment cells, to the num- 

 ber of four or five, often having lodged immediately over the pupil or line 

 of sight. 



Upon removing the thin corneal membrane from the eye, and placing 

 it iu glycerine for a while, in order to render it transparent, the relations 

 of the cysts were easily made out under the microscope. They were 

 found to have very thick walls, which were also laminated. The thick- 

 ness of the walls of the cysts varied considerably; and, as observed in 

 some, was nearly twice as thick as in others. This difference in the 

 thickness of the walls of the cysts is doubtless related to the length of 

 time since the parasite bored its way into the skin. The oldest cysts 

 doubtless having the thickest, the youngest ones having the thinnest 

 wails. 



The entire cyst proper measured about one one hundredth of an inch 

 in diameter, while the halo of surrounding pigment according to its 

 amount would increase this dimension to from one seventy-fifth to one- 

 fiftieth of an inch, which was the size of the papules or swellings caused 

 by the presence of the cysts when the skin was viewed superficially. 



In the most badly infested specimens as many as 480 cysts were 

 counted within an area of a single square inch of skin on tlie sides of 

 the body. Here they seemed to be usually associated iu groups num- 

 bering from one to fifteen to a single scale, and imbedded in tlie thin 

 skin covering the scales. They were least numerous on the chin and 

 under side of the jaws, but very numerously embedded in the skin which 

 covered the fins. From this cause the pectorals, ventrals, anal, dorsal, 



