152 



ganglion (fig. 09, o.y.). From this ganglion nerve fibres 

 are given off, which pass through the basement membrane 

 and innervate the various ornrnatidia of the eye (see figs. 

 69, 70). 



Oculomotor nerve (om.n.}. One pair. These arise 

 from the brain immediately behind the optic nerve. Each 

 passes outward behind the optic nerve, and supplies the 

 optic peduncle and the muscles connected with it. 



Antennulary nerve (a. 1 n.). One pair. At each side 

 this nerve appears to be single, but it is composed of two 

 different kinds of fibres, having different functions and 

 arising from different centres in the brain. For this 

 reason the two nerves should be described separately, as 

 in the case of the optic and oculomotor nerves. The main 

 branch innervates the antennule, and is connected in 

 the brain with the fibrils of the median neuropiles. The 

 fibres innervating the olfactory and tactile setae are 

 probably connected with the lateral neuropiles. The 

 otocyst branch is connected with the lateral neuropiles, 

 and also with the globulus. It passes out from the brain 

 together with the fibres of the main branch, but the two 

 kinds soon separate and those innervating the otocyst pass 

 outwards, and the fibres are connected with ganglion cells 

 at the base of the otocyst setae. The antennulary nerve 

 arises from the middle of the ventral surface of the brain, 

 but in Cancer it apparently leaves the brain near the 

 anterior end. 



Tegumentary nerve (t. n.]. One pair of broad nerves, 

 which leave the brain near the postero-lateral corner. 

 Each passes outwards almost at right angles to the longi- 

 tudinal axis, and divides into two main branches. The 

 anterior branch supplies the integument in region of the 

 rostrum. The outward branch sweeps backwards and out- 

 wards, giving off small branches to the integument. 



