ARTHROPODA 267 
which covers the body of the animal is invaginated at the 
mouth, and lines the gullet and the anterior third of the 
stomach. The rest of this organ is lined by large columnar 
Fic. 159.—Longitudinal vertical median section through Cyclops, partly 
diagrammatic. After Hartog. 
1. Cerebral ganglion. 7. Proctodaeum. 
2, Ventral nerve cord, ganglion omitted. 8. Ovary. 
3. Mouth. 9. Uterus. 
4. Stomodaeum. 10. Spermatheca. 
5. Cells lining posterior part of stomach. 11. Eye. 
6. Intestine. 
cells, some of which contain fat globules, and others granules 
which pass into the intestine, and so out of the body. These 
granules have been regarded by some authorities as urinary. 
The intestine stretches from the stomach to the hind end of 
the second abdominal segment, and then passes into a rectum, 
which is lined with a chitinous cuticle continuous at the 
anus with the general chitinous covering of the body. No 
liver diverticula open into the alimentary canal of Cyclops, 
although these structures are found in some other Gnatho- 
stomata, but there are a pair of salivary glands which open 
by a common duct into the oral face of the labrum, a process 
which overhangs the mouth anteriorly. 
No heart exists in Cyclops, but the space in which the 
alimentary canal les contains a colourless fluid, in which 
colourless corpuscles float. The space which contains this 
fluid is much broken up by connective tissue trabeculae and 
strands of muscle, which support the alimentary canal and 
generative organs. The various muscles are striated, and their 
contraction causes the stomach and intestine to move rhythmic- 
