no. 1404. PARASITIC COPEPODS—CALIGIDJE— WILSON. 529 



structure. • It is made up of a narrow oesophagus, a very much wider 

 stomach, a long- and wide intestine, and a short and narrower rectum. 

 Connected with the canal are two pairs of digestive glands, one pair 

 in the anterior portion of the carapace near the margin, and the 

 other in the thoracic area near the mid line. 



3. The alimentary canal is constricted at fairly regular intervals, 

 and in the living animal is in almost constant peristaltic movement, 

 the waves passing alternately backward and forward. 



4. There is no heart nor any organs of circulation. The blood is 

 driven about through the lacunas between the internal organs by the 

 peristaltic movements of the alimentary canal just referred to, and by 

 the respiratory movements of the rectum. In Caligus curias Picker- 

 ing and Dana discovered valvular action at two points, the apex of 

 the posterior thoracic joint and between the basal joints of the second 

 antenna?. No valves have been thus far seen in other species. 



5. Respiration is anal, the posterior portion of the rectum being 

 supplied with the necessary muscles for the pulsating movement. 



6. The muscular system is very highly developed, and can be seen 

 clearly through the transparent covering. All the muscles are plainly 

 striated. 



7. The nervous system consists of a supra- and an inf ra-oesophageal 

 ganglion connected by stout commissures, and the paired nerves arising 

 from them. There is no spinal cord nor any ventral chain of ganglia. 



8. The female reproductive organs consist of a pair of ovaries situ- 

 ated on either side of the dorsal surface of the stomach. From each 

 an oviduct leads back in nearly a straight line into the genital segment 

 where it is strongly convoluted, and finally emerges to the exterior at 

 the posterior margin of the segment. The oviduct is narrow at first 

 and the eggs are simple nucleated cells. On entering the genital seg- 

 ment the duct widens suddenly and its contents become finely granular 

 with yolk particles, and more or less fused. But the eggs quickly 

 separate and clear in the convolutions, and finally emerge in a long, 

 single row of lozenge-shaped forms, each occupying an apartment of 

 its own in the external egg cases. The eggs are fertilized as they issue 

 from the genital segment by sperm from a pair of sperm receptacles 

 situated in the posterior part of that segment. 



!>. The male reproductive organs consist of a pair of testes smaller 

 than the ovaries, but situated in an exactly similar position. From 

 each a \ as deferens leads hack into the genital segment, and there 

 enters one of a pair of spennatophore receptacles situated in the center 

 of each half of the segment. 



Here the sperms are gathered into bunches or spermatophores, cov- 

 ered with a viscid substance, and in this condition they are subsequently 

 squeezed out of these receptacles into the vagina of the female. 



