634 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. XXVII. 



This stream pour.s around the intestine and separates naturally into 

 two side streams running forward past the bases of the swimming legs 

 and sending out lateral streams into each of them, tinally joining the 

 anterior streams from the aorta under the l)rain. On its return the 

 blood percolates through the lateral sinuses of the carapace and, join- 

 ing the streams from the borders of the abdomen, enters the openings 

 at the sides of the triangular base of the heart. 



JS^ervous system (fig. 9). — This consists of a dorsal brain and a ventral 

 chain of six ganglia. The brain is rather small, but well pigmented. 



Fig. 10.— Sexual organs op female aegultjs amekicanus. o, ovary; n. v., oviduct; s. p., semen 

 papill.e: .s. v., semen receptacle; t. p.. tactile papillae at the openings of the oviduct. 



SO as to be prominent l)y contrast with the light-colored carapace. Its 

 ventral portion extends quite a distance in front of the pigmented 

 dorsal portion and is nearly three times as wide. From the anterior 

 border of this ventral portion a pair of nerves extend forward to the 

 anterior antennae. Another pair arise from about the center of the 

 lateral borders and lead to the posterior antennt^?. These two pairs 

 are the only cranial nerves. The ventral ganglia diminish in size 

 rapidl}-; they are distinctly lobed along the sides, but fused through 



