X NERVOUS AND REPRODUCTIVE SYSTEMS 27 1 



consists solely of the cheliceral ueuromere, a hincl-hrain which 

 supplies the pedipalps and four pair of walking legs, and an 

 accessory hrain which supplies the chilaria and the genital 

 operculum. This is continued backward into a ventral nerve-cord 

 which bears five paired ganglia 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 Zimulvs 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 lining the walls of the tubes, and discharges them by a 

 pore one on each side of the Iiinder 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 (Z. polyphe^nus) 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. 



