NO. 2063. tfORTH AMERICAN PARASITIC COPEPODS— WILSON. 659 



in the average diameter. This smooth posterior portion of the 

 stomach passes insensibly into the intestine (i) which is curved a 

 trifle upward nearer to the dorsal surface of the body and opens at 

 the anus (a). The cells of the glandular layer of the stomach and 

 intestine are similar to those of other genera (figs. 123, 126, 133). 

 The frontal gland (fg, fig. 122) is at the extreme anterior portion of 

 the head and is proportionally very small. This genus is not per- 

 manently fastened to its host by any bulla or frontal filament, and 

 hence a much smaller gland is sufficient. The second maxiUae are 

 flattened into a thin ribbon and the maxilUpeds are extremely 

 minute. Hence, there are no excretory glands in either of them, 

 but there is a pair of large glands in what may be called the shoulders 

 of the trunk, opposite the bases of the second maxillae and above 

 the tips of the egg strings (fig. 125). The infra- and supra-esopha- 

 geal ganglia are exceptionally large, and there is not the disparity in 

 size between them that was noted in Achtheres (ig, sg, fig. 122). 



Each ganglion shows the usual nerve connections with the various 

 appendages, but the large posterior nerve (p), which runs back along 

 the floor of the neck and trunk, is given off from the ventral surface 

 of the infra-esophageal ganglion and not from its posterior end. 

 The cement glands are in the posterior part of the body on either 

 side of the intestine. The ovary and uterine processes of the ovi- 

 ducts are arranged similarly to those of Achtheres. On examining 

 cross sections of the second maxillae it is found that in the process of 

 becoming flattened they have also undergone other changes. On 

 the outer surface of the maxilla there is a thin layer of ordinary skin 

 (s, fig. 124); immediately beneath this are the three bundles of 

 muscles (m) symmetrically arranged, one at the center and one at 

 a Uttle distance toward each lateral margin. Each muscle runs 

 along its own cylindrical tube and is distinct from the others, but 

 the tubes are connected across the two intervals by open spaces (o) 

 in which may be found a thin muscular ribbon. That portion of 

 the maxilla on the inner side of the muscles is much thicker than the 

 outer skin and has become sohdified into a homogeneous mass in 

 which there is no longer any distinction of dermis, epidermis, and 

 subcutaneous tissue (n, fig. 121). This mass has every appearance 

 of cartilage and takes a cartilage stain. On the contrary, the blunt 

 claws at the tips of the maxillae take the eosin, but do not take the 

 haematoxyUn. 



TABLE OP SPECIES. 



1. Egg stiings reaching forward nearly to the base of the second maxillae; abdomen 

 reaching backward nearly to the tips of the egg strings. . lizae (Kr0yer), 1863, p. 660. 



1. A long interval between the second maxillae and the egg strings; abdomen scarcely 



reaching the center of the latter 2. 



2. Cephalo thorax much longer than the rest of the body and filiform. 



cygniformis Hesse, 1863. 



