COPEPOD PARASITES AND MUSSEL GLOCHIDIA ON FRESH-WATER FISHES. 357 



new species, while a single female (catalogue no. 43561, U. S. National Museum) has been selected to 

 serve as the type. 



Specific characters of female. — General body form short and squat; cephalothorax three-quarters of 

 the entire length, one-fifth longer than wide, and strongly flattened dorsoventrally ; dorsal surface mod- 

 erately convex, ventral surface flat, witli the mouth projecting but little, if any. 



Antennal area rectangular in outline with rounded corners and projecting strongly anteriorly, so 

 that the bases of both pairs of antennae are carried in front of the body of the carapace. This latter is 

 about as long as wide, is slightly narrowed posteriorly, and shows a distinct dorsal groove and marginal 

 sinus separating the head from the first thorax segment, which is only one-fifth the length of the head. 

 Second (first free) segment abruptly narrowed to half the width of the first and very short; remaining 

 thorax segments also short and narrowed regularly backward; fifth segment concealed dorsally between 

 the fourth and genital segments; the latter considerably wider and three times the length of the fourth 

 segment, with strongly convex sides. Abdomen three-jointed, joints about the same length but nar- 

 rowing posteriorly and indistinctly differentiated; anal laminae small and rectangular, each bearing two 

 setae, of which the inner one is twice the length of the outer, and about the same length as the free thorax 

 and abdomen. 



Egg strings ovate and strongly divergent, only one-fourth longer than wide, and so much inflated 

 that they meet dorsally at the midline; eggs large, arranged in eight or nine longitudinal rows, about 

 seven eggs in the longest rows. First antennae six-jointed, the penultimate and basal joints longer 

 than the others and all the joints heavily armed with setae; second antennae long and stout, the basal 

 joint much inflated and quite convex externally, the terminal claw stout and strongly curved. 



Mouth parts rather small and effectively concealed beneath the upper lip, not projecting as in other 

 species but flattened with the rest of the ventral surface. Mandibles with a narrow cutting blade, 

 armed with setae along the inner margin only; palp about as long as the cutting blade, armed with setae 

 or toothed along the posterior margin. 



First maxillae with a large base and two stout setae; second maxillae with a straight cutting blade, 

 fringed with setse along both margins, basal joint large and rectangular. Endopods of first and 

 foiulh legs much longer than exopods, the two rami of the second and third legs equal; exopod of fourth 

 legs two-jointed. The arrangement of the spines and setae is as follows: First exopod, l-o, o-i, 11-5; 

 endopod, o-i, 0-2, 1-4; second exopod, i-o, o-i, 0-6; endopod, o-i, 1-2, 0-5; third exopod, 0-0, o-i, 0-5; 

 endopod, o-i, 0-2, 0-5; fourth exopod, 0-0, 0-4; endopod, o-i, 0-2, 0-5. 



Qjlor (preserved material), yoiuig females a uniform creamy white without pigment; in later 

 development black pigment appears in scattered spots on the dorsal surface of the carapace and gradu- 

 ally covers the entire copepod, including even the swimming legs and anal laminae and setae but not 

 the second antennae. 



Total length, 0.70 mm.; carapace, 0.50 mm. long, 0.40 mm. wide. Egg strings, 0.35 mm. long, 0.23 

 mm. wide. 



(nigritus, blackened.) 



Remarks. — This tiny species may be recognized at once by the jet-black color of the mature adults 

 and by the very short and thickset egg strings. 



It can not be very common, since only the single lot has been obtained from many hundreds of 

 largemouth black bass which have been examined for copepod parasites. It seems to take the place 

 on this bass of cceruleus upon the other Centrarchidae, being associated with Lampsilis glochidia. 



Ergasilus megaceros, new species. (PI. lxvi, fig. 49; pi. Lxvni, fig. 57-61.) 



Host and record cf specimetis. — Four females, two of which had egg strings, were taken from the 

 lamellar plates in the nasal fossae of a Fulton cat, Icialurus anguilla, captured at Fairport, Iowa, May 

 16, 1914. Three of these specimens have been given catalogue no. 43548, U. S. National Museum, and 

 become cotypes of the new species, the fourth and best one (catalogue no. 43544, U. S. National Museum) 

 becoming the type. 



Specific characters of female. — General body form long and slender; cephalothorax ovate, one-half 

 longer than wide, narrowed and pointed anteriorly, squarely rounded posteriorly; first thorax segment 

 as wide and half as long as the head and separated from the latter by marginal sinuses and a distinct 

 dorsal groove; eye far forward just behind the bases of the first antennae; thorax segments diminishing 

 regularly in size backward, the fifth one very short; genital segment the same width as the fourth seg- 



