x: NERVOUS AND REPRODUCTIVE SYSTEMS 271 
consists solely of the cheliceral neuromere, a hind-brain which 
supplies the pedipalps and four pair of walking legs, and an 
accessory brain which supples the chilaria and the genital 
operculum. This is continued backward into a ventral nerve-cord 
which bears five paired gangha supplying the five pairs of gills 
and three pairs of post-branchial ganglia ; the latter are ill-defined 
and closely fused together. As was mentioned above, the whole 
of the central nervous system is bathed in the blood of the 
ventral sinus. 
The sense-organs consist of the olfactory organ of Patten, the 
median and lateral eyes, and possibly of certain gustatory hairs 
upon the gnathobases. The lateral eyes in their histology are 
not so differentiated as the median eyes, but both fall well 
within the limits of Arachnid eye-structure, and their minute 
anatomy has been advanced as one piece of evidence amongst 
many which tend to demonstrate that Limulus is an Arachnid. 
Both ovaries and testes take the form of a tubular network 
which is almost inextricably entangled with the liver. From 
each side a duct collects the reproductive cells which are formed 
from cells hning the walls of the tubes, and discharges them by a 
pore one on each side of the hinder surface of the genital oper- 
culum. As is frequently the case in Arachnids the males are 
smaller than the females, and after their last ecdysis the pedipalps 
and first two pairs of walking legs, or some of these appendages, 
end in slightly bent claws and not in chelae. Off the New Jersey 
coast the king-crabs (L. polyphemus) spawn during the months of 
May, June, and July, Lockwood states at the periods of highest 
tides, but Kingsley ' was never “able to notice any connexion 
between the hours when they frequent the shore and the state 
of the tide.” “When first seen they come from the deeper 
water, the male, which is almost always the smaller, grasping 
the hinder half of the carapace of the female with the modified 
pincer of the second pair of feet. Thus fastened together the 
male rides to shallow water. The couples will stop at intervals 
and then move on. Usually a nest of eggs can be found at each 
of the stopping-places, and as each nest is usually buried from 
one to two inches beneath the surface of the sand, it appears 
probable that the female thrusts the genital plate into the sand, 
while at the same time the male discharges the milt into the 
1 J. Morph. vii., 1892, p. 35. 
