194 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



two of the above-mentioned parasites attached to it, and 

 another with one, were found. The parasites were 

 embedded in the tissues at the anterior end of the dorsal 

 fin. On dissecting one out it was found that the head had 

 penetrated to the visceral cavity. Fig. 6 represents the 

 natural size of the sprat and its parasite, and also shows 

 the position of attachment. Fig. 7 represents a dissection 

 showing the head of the parasite passing into the visceral 

 cavity. Figs. 8 and 9 represent two views of the head 

 and illustrate the difference between L. encrasicoli and 

 L. sjirattce. 



The following ecto-parasites of fishes have been taken 

 within the past few years, but illustrations are now given 

 to show the differences in the appendages. 



Lernseenicus sprattae (Sowerby). Plate II, figs. 1-5. 



This parasite is not uncommon on the sprats captured 

 along the Lancashire coast. It differs in the manner of 

 attachment to its host from L. encrasicoli. All the 

 specimens of L. sprattaz that we have seen were attached 

 to the eye, as shown in the illustration. The barbed 

 head is inside the eye, and the parasite apparently feeds 

 on the semifluid matter. The neck of the parasite is 

 corrugated for some distance from the point of its attach- 

 ment to the body. In L. encrasicoli the neck is quite 

 smooth. The lateral projections of the head differs 

 somewhat in the two species. In L. sprattce they are 

 directed backwards, and in L. encrasicoli they are nearly 

 at right angles to the head. The appendages in the two 

 species appear to be identical, and consist of one pair of 

 antennules, one pair of antennae, and four pairs of 

 rudimentary feet. The four pairs of feet have probably 

 remained in the same condition from the free-swimming 

 larval period. 



