II REPRODUCTIVE ORGANS 31 
small ganglionic enlargements occur. In Apodidae, on the other 
hand, those segments which carry more than one pair of 
appendages have as many pairs of ganglia, united by transverse 
comimissures, as they have limbs. 
A stomatogastric nervous system exists in 4pus, where a 
nerve arises on each side from the first post-oral commissure, 
and runs forward to join its fellow of the opposite side on the 
anterior wall of the oesophagus. From the loop so formed a 
larger median and a series of smaller lateral nerves pass to the 
wall of the alimentary canal. A second nerve to the oesophagus 
is given off from the mandibular ganglion of each side. 
Reproductive Organs.—In Chirocephalus the ovaries (Fig. 
2, Ov) are hollow epithelial tubes, lying one on each side of the 
alimentary canal, and extending from the sixth abdominal 
segment forwards to the level of the genital opening ; at this point 
the two ovaries are continuous with ducts, which bend sharply 
downwards and open into the single uterus contained within 
the projecting egg-pouch and opening to the exterior at the 
apex of that organ. Short diverticula of the walls of the uterus 
receive the ducts of groups of unicellular glands, the bodies of 
which contain a peculiar opaque secretion, said to form the egg- 
shells. In Apodidae the ovaries are similar in structure, but 
they are much larger and branch in a complex manner, while 
each ovary opens to the exterior independently of the other in 
the eleventh post-cephalic segment; nothing like the median 
uterus of the Branchipodidae being formed. The epithelium of 
the ovarian tubes proliferates, and groups of cells are formed : 
one becoming an ovum, the others being nutrient cells like those 
which will be more fully described in the Cladocera. 
In Chirocephalus the testes are tubes similar in shape and 
position to the ovaries, each communicating in front with a 
short vas deferens, which dilates into a vesicula seminalis on its 
way to the eversible penis; an essentially similar arrangement 
is found in all Branchipodidae, but in Apodidae and Limnadiidae 
there is no penis. 
All the Branchiopoda are dioecious,’ and many are partheno- 
genetic. Among Branchipodidae Artemia is the only genus 
known to be parthenogenetic, but parthenogenesis is common in 
' Bernard’s statement that Apuws is hermaphrodite seems based on insufficient 
evidence. 
