90 BALANID^. 



figured), running dorsally into the body, so that we have 

 seven nerves rising from the under surface of the infra- 

 cesophageal ganglion. I need only farther add, that on 

 each side of this ganglion, between the nerves going to the 

 first and second pairs of cirri, there is a moderately sized 

 nerve (&), which appeared to run into the muscles of the 

 thorax : a nerve in a similar position is figured by Milne 

 Edwards in Maia. 



The circa- oesophageal chord (c, c) nearly equals in length 

 the whole distance from the centre of the main ganglion to 

 the posterior end of the thorax. This collar bows out on each 

 side, where passing the oesophagus (ce), which is seated at its 

 anterior end. From the collar a branch is given off on 

 each side, which I traced as far as between the mandibles 

 and maxilla? ; from analogy with other Crustaceans, it 

 perhaps runs to the mandibles. The collar has not a 

 transverse commissure, such as described by Milne Edwards 

 in the Podophthalmia, and as figured by Van de Hoeven in 

 Limulus. 



The supra- oesophageal ganglions (b) present a singular 

 contrast with the infra-cesophageal ganglion in their little 

 development, size, or degree of confluence. They lie di- 

 rectly under the basal edge of the labrum. They are 

 laterally quite distinct, and consist merely of a slight en- 

 largement of the circa-cesophageal chord. From the ante- 

 rior edge of each ganglion, a broad nerve (/) extends for 

 some distance in a straight line, and, on close examination, 

 can be seen to be formed of two nerves closely united, of 

 which the inner and smaller one, after a space, appears to 

 cross over the larger nerve : both become at this point 

 tortuous, and, giving off branches {m, m), form a plexus. 

 The two nerves (/) then bend inwards, and almost 

 touching each other, run down, together with the two 

 ovarian simple ducts, along the rostral compartment of the 

 shell. No doubt, if the smaller branches from these nerves 

 could be traced, they would be seen to form a network over 

 the whole sack ; and would therefore enclose, as in a cage, 

 the rest of the nervous system. These nerves correspond, I 

 believe, to the two pair of antennular nerves of ordinary 

 Crustaceans, and hence 1 will call them bv this name. 



