458 EEPOET OF COMMISSIONER OF FISH AND FISHERIES. 



ure and migrate from oue to another. Three species belonging to this 

 group were taken at the surface with the to wing-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 

 Lernmonema radiatum (Plate YII, 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 Branchiohdella Eaveneliiy (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 " sting-rays,'' 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 Cystohranclms 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 pisciilentiis^) 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 

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

 darker green and brown specks, often with whitish transv^erse bands 

 anteriorly, and a white ring behind the head, at the constriction 5 some- 

 times there is a narrow pale dorsal line. 



A long, slender, sub-cylindrical leech, the Pontohdella rapaxY., (Plate 

 XYIII, fig. 91,) is quite common on the upper side of the " summer- 

 flounder," {CJicenopsetta 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 j the suckers are pale greenish white. The young are reddish 

 brown, without spots. 



A species of Pontohdella was found adhering to Mysis Americana., 

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

 mal habit is uncertain. 



The MalacobdeUa ohesa Y. (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 "long clam," (Mya arenaria.) 



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

 and more slender, which lives in the same way in the/' round clam" 

 (Venus mercenaria.) 



The Myzobdella InyHhris is a small leech, which lives on the " edible 

 CYiih^^ {CaUinectefi hastatHs,) adhering to the soft membranes between 

 the joints and at the base of the legs. 



