NO. 1404. PARASITIC COPEPODS—CALIGID.E— WILSON. 529 



structure. It is made uj) of a narrow (lesophao-as, a very much wider 

 stoiuacli, 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 reguhir intervals, 

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

 the waves passing alternatel}" ])ackward and forward. 



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

 driven about through the laciuue between the internal organs ])y the 

 peristaltic movements of the alimentary canal just referrc^d to, and by 

 the respiratory movements of the rectum. In Culigax cmiKs Picker- 

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

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

 antenna?'. No valves have l)een thus far seen in other species. 



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

 supplied with the necessary nuiscles for the pulsating movement. 



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

 clearly through the transparent covering. All the nuiscles are plainly 

 striated. 



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

 ganglion connected by stout commissures, and tlie i)aired nerves arising 

 from them. There is no spinal cord nor aiw 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 baciv in nearly a straight line into the genital segment 

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

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

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

 ment the duct widens suddenl}' and its contents become finely granular 

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

 separate and clear in the convolutions, and finall}^ emerge in a long, 

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

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

 from the genital segment l)y sperm from a pair of sperm receptacles 

 situated in the posterior part of that segment. 



9. The male reproductive organs consist of a pair of testes smaller 

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

 each a vas deferens leads back into the genital segment, and there 

 enters one of a pair of spermatophore 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 subsequenth* 

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



