280 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



perhaps never without injury to the jaws of the fish. The fishermen, 

 therefore, consider the insect as essential to the life of the fish, for when 

 it is taken out, and the fish is thrown again into the water, he is inca- 

 pable of swimming and soon dies. I endeavored in numerous instances 

 to preserve both the insect and the fish from injury, but was always 

 obliged either to destroy the one or to injure the other. I have some- 

 times succeeded in taking out the insect in a brisk and lively state. As 

 soon as he was set free from my grasp, he immediately scrambled nim- 

 bly back into the mouth of the fish and resumed his position. In every 

 instance he was disgustingly corpulent and unpleasant to handle, and it 

 seemed, whether he have obtained his post by force or by favor, whether 

 he be a mere traveler or a constant resident, or what else may be his 

 business where he is found, he certainly has a fat place of it, and fares 

 sumptuously every day. 



The drawings annexed to this account were made from the live insect, 

 and from the fish out of whose mouth he was taken. I had no books to 

 refer to then ; but examining the Systema Natures of Linnaeus, I was 

 surprised to find so exact a description of the insect as follows (see 

 Salvii Editio, Holmiae, 1763, 1060, also Trattner's Vienna edition, same 

 page) : 



"Insect, apt. Oniscus, Pedes XIV. 

 Antennae setacese. 

 Corpus ovale. 



" O. physodes, abdomine subtus nudo cauda, ovata ; habitat in pelago j 

 corpus praeter caput, et caudam ultimatum, ex septem segmentis trunci, 

 et quinque caudae. Antennae utrinque duo, breves. Caudae folium ter- 

 minale omino ovatum ; ad latera utrinque subtus auctum duobus pete- 

 olis diphyllis, foliolis lanceolatis, obtusis, cauda brevioribus. Caudae 

 articuli subtus obtecti numerosis vesiculis longitudine caudae." 



From the particularity with which the Oniscus physodes is described by 

 Linnaeus, it is evident that he had the insect before him, or a description 

 by an attentive observer. It appears also from the " habitat in pelago," 

 that the 0. physodes, if this be the insect, is found detached from his con- 

 ductor. There are a few points in which the 0. physodes differs from my 

 insect. I did not observe the antennae, perhaps for want of sufficient 

 attention, or of a microscope. The peteoli of the tail were not, to 

 appearance, two-leaved, and I am certain that the segments of the tail, 

 and the tail itself, were without the vesiculi longitudine caudae. 



There are many circumstances, to ascertain which is essential to the 

 natural history of this insect. The fish whose mouth he inhabits comes, 

 about the same time with the shad, into the rivers of Virginia from the 

 ocean, and continues to travel upward from the beginning of March to 

 the middle of May ; as long as they are caught upon their passage uj) 

 the river, they are found fat and full of roe. Every fish which I saw 

 had the Oniscus in his mouth, and I was assured, not only by the more 

 ignorant fishermen, but by a very intelligent man who came down now 



