414 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxii. 



The reproductive organs are very prominent, being colored a cinna- 

 mon brown, which stands out in strong contrast to the surrounding 

 gray and yellow. From the anterior end of each of the large testes a 

 vas efferens leads forward to the semen receptacle, which is situated in 

 the second thorax segment. 



The vasa def erentia given otf from the anterior end of this receptacle 

 are very large at their bases and project somewhat into the first thorax 

 segment. They taper gradually backward to the fourth segment, where 

 they curve down on the outside of the vasa eli'erentia and meet below 

 in the common ejaculatory duct. 



Color of the Lake Champlain specimens a grayish green, similar to 

 that of the female, the ventral surface of the thorax in the male and 

 in several young females taken with them being sparsely covered with 

 small spots of a brick- red pigment. 



Color of the Lake Maxinkuckee specimens a light grayish brown, 

 without any tinge of green. Eyes dark brownish black, brain a pur- 

 plish hue, reproductive organs a dark cinnamon brown. 



The ventral surface of each testis has a long line of the same dark 

 brown running through the center lengthwise, the line becoming 

 bifurcate toward the posterior end. 



On the ventral surface of each joint of the thorax at the center and 

 on the basipods of the swimming legs are small spots of brick-red 

 pigment. 



Total length 5-tJ nun.; length of carapace 4.5 mm., of thorax 1.5 

 nun., of abdomen 1.35 mm. Width of carapace 1.8 mm. 



II. THE LARVA OF ARGULUS FUNDULI Kroyer. 

 Plate XXX, figs. 10-14. 



Only a single larva, that of Argulus megaloim^ or the true salt water 

 Argulid.s has been described up to the present time. 



The one here presented is therefore the second and is of peculiar 

 interest in that it substantiates many of the characters in which the 

 megalopn larva was found to differ from the fresh-water forms. Two 

 ripe females of Ai-gulx.s fnndul! were obtained from Fundidm hetero- 

 ditus at Beaufort, North Carolina, on August 1, 1905. On being 

 placed in fresh sea water one of the females deposited her eggs; these 

 were then kept in a small glass surrounded by running sea water at a 

 constant temperature of about 27 C. The eggs began to hatch on 

 August 22, eighteen days after being laid. This is in marked contrast 

 with the megaJo]>s larva?, which required sixty days of incubation, but it 

 shows that there is the same difference between the salt-water forms 

 that we find in fresh -water species. 



The eggs of ArguhiH fundxili^ therefore, among the salt-water forms 

 correspond with those of A. aniericanus and A. maeulosus from fresh 



