NO. 2194. NORTH AMERICAN PARASITIC COPEPODS— WILSON. 67 



The liist antennae are turned back along the surface of the head 

 and are indistinctly three-jointed, the terminal joint chelate, a 

 strongly curved claw shutting down against a short projection on 

 the inner margin of the second joint. The basal joint is a trifle 

 wider and nearly twice as long as tlie second joint. There is appar- 

 ently no protrusible proboscis, since none can be seen in any of the 

 specimens, but fortunately those from Beaufort, North Carolina, 

 were examined alive and a proboscis could then be seen projecting 

 from the ventral surface. The numerous muscles also connected with 

 the mouth opening must be used for protrusion and retraction. And 

 sections of the head of one of these preserved specimens show clearly 

 that the only reason why no proboscis is seen is that it was tightly 

 withdrawn into the head at the time of death. The mouth is a simple 

 opening and is surrounded by a narrow and ciliated membrane. On 

 the inside of the mouth tube and projecting from its dorsal surface 

 into the lumen can be seen two large and stout spines, bipartite near 

 their tip, which probably represent rudimentary mandibles. On 

 either side of the mouth are the maxillae, which are two-jointed, the 

 basal joint stouter than the terminal and nearly twice as long, some- 

 what swollen at the center, and armed on its ventral surface with two 

 short knobs placed side by side; the terminal joint is tipped with a 

 rather stout claw, longer than the joint itself and slightly curved. 



Ui>on the ventral surface of the neck where it joins the head are 

 the four pairs of swimming legs. These diminish in size regularly 

 backward, the first two pairs being biramose and the last two pairs 

 uniramose, all the rami two-jointed. The basal plates are broadly 

 triangular, the base of the triangle jointed to the thorax, while to 

 the apex are attached the rami. The joints of these rami are of 

 about the same size and the terminal one is tipped with seven setae, 

 the central three of Avhich are considerably longer than the others. 



Internal structure. — Inside of the anterior end of the genital seg- 

 ment may be seen the ovaries, which are strongly flattened between 

 the intestine and the dorsal wall of the segment. They are oval 

 in outline, the broad ends anterior, from which the oviducts extend 

 obliquely downward and backward to the ventral surface. There 

 they increase in diameter, become straight and cylindrical, and ex- 

 tend back to the vulvae. The cement glands are straight and narrow 

 and do not show any segmentation; the duct is about the same length 

 as the glandular portion. 



The esophagus is slightly enlarged at either end and contracted 

 at the center; the anterior enlargement is probably temporary and 

 due to the pulling up of the dorsal wall during retraction; the 

 posterior enlargement is permanent. The stomach is narrow and at 

 its posterior end, Avhere it passes into the neck, it is bent at right 

 angles. The intestine fills the whole lumen of the neck and abdomen, 



