CRUSTACEAN PARASITES OF FRESH- WATER FISHES. 663 



length of the aniinal, sleuder, liuear, provided with about twenty series 

 of eg-gs longitudinally, and two, or at the most three, transversely." 



ACHTHERES Lac^ Kroyer. 



Op. cit., pp. 274, 275, pi. 17, fig. 6, 1863 



This species is described by Kroyer from a "North- American species 

 of ])erch, {Perca Laca,y^ aiu\ should probably be included in this list- 

 The following is a translation of the diagnosis : "Arms, by which the 

 animal is attached, scarcely or a little longer than the head, stout, ar- 

 cuate ; bulla distinctly petiolate. Body neither anuulated nor longitu- 

 dinally sulcated; external ovaries much shorter tliau the auimal, about 

 equaling the body; stout, obclavate, filled with about twelve series of 

 eggs longitudinally, and transversely, with four anteriorly, three in the 

 middle, and two posteriorly." , /)ie^ 



Lern^opoda fontinalis, sp. nov. (Plate III, fig. 12, lateral aud^^;^-^ 

 dorsal views ; figs. 13 and 14, details.) a ■ J Wj^M-^^ '^' 



Female. — Head nearly as long as the body, and longer than broad. 

 Bod^', short and thick, not very much longer than broad. Prehensile 

 hooks (fig. 14, a) stout, nearly half as long as the head, with a small 

 jDapilliform process on the inside of the penultimate segment; terminal 

 segment rather slender, tapering, straight to near the tip, which is 

 suddenly curved backward, and terminating in an acute point. Arms 

 by which the animal is attached nearly or quite as long as the body ; 

 bulla with an elongated petiole, and broadly expanded at the extremity ; 

 ova-sacs as long as or a little longer than the bodj^, with three or four 

 series of eggs transversel\% and ten to twenty longitudinally. 



Entire length, from mouth to extremities of ova-sacs, 5""; diameter 

 of body, r"'".5 ; length of ova-sacs, 2""" ; diameter of ova-sacs, O^^.To. 



This species is apparently allied to the i. carpionis of Kroyer, (op. cit., 

 p. 277, pi. 14, fig. 4,) and seems to belong to this genus as understood 

 by Kroyer. In our species, the antennulse (fig. 13, c) are very short and 

 small processes, not reaching beyond the mouth. The autennse (tig. 13, 

 d) are large, and extend as far forward as the mouth, and each one is 

 divided at the extremitj^ into three lobes, of which the median lobe is 

 again minutely bilobed, or obscurely forcipnlate, while the lateral ones 

 (dorsal and ventral in relation to the animal) are armed with numerous 

 minute hooks, and on the outer side, just below the tip, there is another 

 similar lobe armed with minute hooks. The palpi-like appendages (tig. 

 13, h) on each, just below the mouth, are each tipped with three papilla- 

 like lobes. The mandibles (fig. 14, h) are each armed with four stout 

 distal and three much smaller proximal teeth. 



Found upon the brook-trout, {Salmo fontinalis,) at Norway, Me., in the 

 trout-breeding establishment of Mr. A. B. Crockett. The specimens 

 were all attached to the gills, and were apparently the cause of the 



