COPEPOD PARASITES AND MUSSEL GLOCHIDIA ON FRESH-WATER FISHES. 359 



as the second maxillse, cutting blade turned forward at right angles to the base, very wide and armed 

 with setae along both margins; palp short and narrow, with a row of comblike teeth along its inner margin. 

 First maxillas small and inconspicuous, not visible in side view owing to the fact that they are covered 

 by the upper lip; second maxillae small, the cutting blade narrow and armed with setae along both 

 margins. This species resembles elegans in having the endopod of the first legs as well as the exopods 

 of the fourth pair two-jointed. 



The arrangement of the spines and setae is as follows: First exopod, i-o, 1-2, U1-5; endopod, o-i, 

 n-6; second exopod, i-o, i-i, 1-7; endopod, o-i, 0-2, 1-5; third exopod, i-o, n-o, 1-5; endopod, o-i, 

 0-2, 11-5; fourth exopod, 0-0, 1-5; endopod, o-i, 0-2, 1-4. The oviducts are so arranged that when 

 filled with ripening eggs they do not distort the shape of the cephalothorax as in other species. 



Color, a transparent grayish white, oviducts and egg strings dark yellow, ventral surface covered 

 with an interlaced network of lines and patches of indigo blue. 



Total length, 1.40 mm.; cephalothorax, 0.85 mm. long, 0.30 mm. wide. Egg strings, i mm. long. 



(elongatiis , elongate, alluding to the general body form.) 



Remarks. — This species is unique in its general body form as well as in its habitat and may be 

 recognized by either peculiarity. It will be remembered that in the paddle fishes, to which the spoon- 

 bill cat belongs, the gill rakers are very long and slender and in a double series on each gill arch, the 

 series separated by a broad membrane. These copepods were fastened to the rakers, sometimes on the 

 outside, sometimes on the inside between the raker and the membrane, with their head indifferently 

 in either direction, toward the arch or away from it, and the short but stout second antennae grasped the 

 raker firmly enough to make around it a groove from which the copepod could not be separated except 

 by cutting the raker close to the antennae. 



So far as known this is tlie only instance of any of the Ergasilidae fastening itself to the bony gill 

 rakers instead of the soft filaments, and this makes the strength of the attachment the more worthy of 

 notice. 



Apparently this species is not connected with any glochidium, but this may be changed later when 

 the spoonbill cat has been further and more extensively examined. The body is fully as thick as it 

 is wide and the carapace fits snugly on the general contour, giving the copepod a peculiarly clean and 

 graceful appearance. 



Ergasilus elegans, new species. (PI. LXix, fig. 67-73.) 



Host aiid record of specimens. — ^This species was captured several times in the tow at Patterson 

 Lake and ' ' Sunfish Lake ' ' before it was found on any fish host ; these free-swimming specimens have been 

 given catalogue no. 47767 , U. S. National Museum, and are all without egg strings. A second lot with egg 

 strings was obtained from the gills of the bullhead, Ameiurus melas, caught in "Simfish Lake, " August 

 24, 1914; they have been numbered catalogue no. 47768, U. S. National Museum. A single female 

 has been selected from this lot to serve as the type of the new species, with catalogue no. 47769, U. S. 

 National Museum. A few were also obtained from the gills of the long-nosed gar, Lepisosteus osseus, in 

 the Mississippi near Fairport, Iowa, catalogue no. 47766, U. S. National Museum. Others were foimd 

 on the gills of the short-nosed gar, L. platostomus, from Patterson Lake, August 6, 1914. 



Specific characters of female. — General body form elongate; cephalothorax one-half longer than wide, 

 the first thorax segment distinctly separated from the head and somewhat narrower; carapace well 

 rounded and scarcely projecting anteriorly; antennal area poorly differentiated. 



Second, third, and foiulh thorax segments about the same length and diminishing regularly in width, 

 fifth segment scarcely visible; genital segment barrel-shaped, with moderately projecting sides. Abdo- 

 men three-jointed, joints about the same length but diminishing slightly in width; anal setae as long as 

 the last two segments, twice as long as wide, with square comers, each tipped with two setae, a longer, 

 jointed one at the inner comer, and a shorter oblique one at the outer comer. 



Egg strings less than half the length of the body and rather wide; eggs exceptionally large and 

 arranged in two rows, 15 or 18 eggs in each string. First antennae six- jointed and heavily armed with 

 setas; second antennse very long and slender, basal joint short and not swollen; second joint and terminal 

 claw the same length , the former with a small spine on its ventral surface, the latter bent into a half circle. 

 Mandibles with a rectangular base abmptly narrowed into the neck, which is half as long as the base 

 and is tipped with a triangular cutting blade, heavily fringed with setae around its entire margin; palp 

 as long as the cutting blade, narrow and armed along the ianer margin with a row of heavy, comblike 



