290 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 39. 



Tn none of the specimens thus far examined do they show any 

 structure. In many cases, especially in the youngest females found 

 attached to the fish's gills and in nearly all the adults that are loaded 

 with Vorticellidge, these connective tissues are filled with oil globules, 

 which are especially abundant between the stomach and the dorsal 

 wall of the carapace. These globules vary in color from orange to 

 rusty brown, but thus far they have never been found symmetrically 

 arranged, as Hertog has noted in the morphology of Cyclops (1888, 

 p. 21). 



The muscles are all well striated and are made up exclusively of 

 contractile substance without any nuclei or sarcolemma. The cir- 

 cular muscles which produce the peristaltic movements of the stomach 

 and intestines are inserted in the outer layer of connective tissue 

 surrounding those organs. The muscles which cross more or less 

 of the coelomic space are inserted directly in the epidermis, and so 

 far as observed there are no tendons. 



The coelomic fluid is colorless and the corpuscles are ama3biform 

 as in the free -swimming copepods. No heart is present, but the 

 circulation of the coelomic fluid is accomplished by the digestive 

 system, as will be described under the latter. 



THE DIGESTIVE SYSTEM. 



The alimentary canal begins in a sort of mouth or oral cavity, 

 bounded by the mouth parts and projecting lips. From this a 

 narrow gullet passes upward and backward and opens into the 

 stomach on the ventral surface of the latter a little in front of its 

 center. The stomach is separated by a well-defined constriction at 

 the posterior border of the second thoracic segment from the intes- 

 tine, which in the abdomen passes insensibly into a rectum and ends 

 at the anus, situated between the anal laminse and nearer the ventral 

 than the dorsal surface. 



The mouth is bounded by the labrum in front and by the labium 

 behind, both of which project from the ventral surface of the head, 

 thereby increasing the size of the oral cavity. 



Laterally the mouth is bounded by the sockets and bases of the 

 mandibles and maxillae; these mouth parts are described under each 

 of the subfamilies. 



The gullet leads directly from the mouth cavity upward and back- 

 ward to the stomach; it is not bent at an angle as in Cyclops, but is 

 evenly curved. It enters the stomach on the ventral surface of the 

 latter, some distance behind the anterior end (fig. 15). 



The stomach is a long and pear-shaped sac, extending back to the 

 second (first free) thorax segment. The anterior end is considerably 

 larger than the posterior, and from it rounded processes or lobes 

 extend forward and sidewise, in all five in number (fig. 13) . From the 



