164 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [458] 



ure and migrate from one to another. Three species belonging- to this 

 group were taken at the surface with the towing-nets. The Lerneans 

 are remarkable creatures. The females are generally very curious in 

 form and very much larger than the more active and less abnormal males, 

 and they are very low in structure, the reproductive system being enor 

 mously developed at the expense of nearly all the other organs. They 

 live upon the exterior and gills of fishes, with the head deeply buried 

 in the flesh, and subsist by sucking the blood of their victims. The 

 Lerncconema radiatum (Plate VII, fig. 30) is very common on the men 

 haden, and is also found on the alewives. 



There are many kinds of parasitic leeches. One of the most remark 

 able is the BrancMoMella Ravenelii, (Plate XVIII, fig. 89.) This genus 

 is peculiar in having broad, foliaceous, lobed or scolloped gills along 

 the sides of the body. The large species figured was found several times 

 on the large &quot; sting-rays,&quot; several of them usually occurring together, 

 on a large spot which had become sore and much inflamed by their re 

 peated bites. It is a very active species. 



The Cystobranchus vividus is a much smaller and quite slender leech, 

 which has small, papilliform, whitish gills that alternately contract and 

 expand along the sides of the body, each surrounded by a semicircular 

 white spot. The colors are brownish or purplish, with three rows of 

 small white spots on the back. This species is frequent on the common 

 minnow, (Fundulus pisculentus,) in autumn and winter, and lives both 

 in brackish water and fresh water. With the last, on the minnows, is 

 found another slender leech, destitute of gills ; this is the Iclitliyobdella 

 FunduU. It has, like the last, four ocelli. The color is pale green with 

 darker green and brown specks, often with whitish transverse bands 

 anteriorly, and a white ring behind the head, at the constriction ; some 

 times there is a narrow pale dorsal line. 



A long, slender, sub-cylindrical leech, the PontoMella rapaxV., (Plate 

 XVIII, fig. 91,) is quite common on the upper side of the &quot; summer- 

 flounder,&quot; (Clicenopsetta ocellaris.) It is a very active species, dark olive 

 or brown in color, with a row of square or oblong whitish spots along 

 each side ; the suckers are pale greenish white. The young are reddish 

 brown, without spots. 



A species of Pontoldella was found adhering to Mys-is Americana, 

 near New Haven, May 5, in three instances, but whether this be its nor 

 mal habit is uncertain. 



The MalacoMella obesa V. (Plate XVIII, fig. 90) .is a large, stout, 

 yellowish white leech, often two inches long, which is quite common in 

 the branchial cavity of the &quot;long clam,&quot; (Mya arenaria.) 



The MalacoMella mercenaria V. is another similar species, but smaller 

 and more slender, which lives in the same way in the &quot; round clani&quot; 

 (Venus mercenaria.) 



The MyzoMella lugulris is a small leech, which lives on the &quot; edible 

 crab&quot; (Callinectes hastatus,) adhering to the soft membranes between 

 the joints and at the base of the legs. 



