.'. PHYSIOLOGICAL SEJUK8. 



D. IS. Two specimens of the nervous system of a Barnacle 



if era). The small bilobed cerebral ganglion 



lit- on the anterior wall of the oasophagus at its entry 



int.* the oil' a large nerve on either side 



; u' jiediiiicle. an.l an extremely line pair (not visible in 

 tin- -pec-mien...) from it- anterior surface to the vestigeal eye. 

 The visceral nerves arise from the circumoesophageal 

 connectives close behind the cerebral ganglion. The suh- 

 OBtOphageal ganglion is the largest and most important 

 nerve-centre in the body ; it sends a large pair of nerves 

 from its dorsal surface to the adductor scutarum muscle, 

 and also supplies the mouth-parts and first pair of cirri. It 



>llowed by a chain of four segmentally placed ganglia, 

 each of which gives on" a pair of nerves to the cirri of its 

 *egni"iit : tin- terminal ganglion is slightly larger than the 

 others, and represents a fusion of two, it innervates the 

 last two pairs of cirri and the penis. The ganglia arc 

 ly concentrated in a transverse direction, but the 

 connectives particularly at the anterior end of the chain 

 are distinctly separate. Between them runs a small median 

 nerve (n..t \isible in the specimens), that arises in the sub- 

 OBtophmgeal ganglion ami is ultimately distributed to the 



nu. In the upper specimen the nervous system is 

 n in an isolated state, and in the lower from the right 



within the body. 0. C. 1302 K. 



ivel, Arch. Zool. Exp., ser. 3, t. i. 1893, p. 489. 



D. 13 A Stomatopod (Lytiomjuilla, sp.) with the nervous system 

 1 from al.ove. The small |uadrilateral eerdiral 

 - in the second cephalic segment; it gives 

 off three large pairs of nerves respectively to the eyes and 

 he two pairs of antenn:e. a- \\ell as a few delicate 

 iches (not -hown in the specimen) to the neighbouring 

 mntcles and integument. The circumoosophageal con- 

 nectives, owing -"iided character of the head- 

 are remarkably long in front of the mouth; on 

 r>1tl ! te oesophagus they swell slightly to form a 

 mall o?ophageal ganglia, that give off the visceral 

 .-OB and are united together l.chind the oesophagus bv .1 

 ingle rommkHure. A short distance behind the oesophagus 



