468 DISCOVERY REPORTS 



and is a posterior valve nerve. From the lower edge of the stalk of the posterior lobe 

 a nerve curves forwards around the anterior hypostomal apodeme and runs to the 

 maxillule. 



From the hinder margin of the nerve ring there arise two pairs of nerves, one situated 

 just below the paired stalk of the ventral chain, and another pair more laterally. They 

 are the first and second maxillary nerves. 



The remainder of the ventral chain consists of a nervous mass which is triangular in 

 both dorsal and lateral aspects (Figs. 9,106). It is joined to the nerve ring by the paired 

 stalk already mentioned, and is more condensed than in any other Cypridinid I have 

 studied. 



Ventrally, at the root of the stalk, it gives rise to the small nerves running to the first 

 trunk limbs. Dorsally at about the middle of its length there are two small swellings, 

 from which arise a pair of nerves which run forwards, the third maxillary nerves. These 

 innervate the musculature of the vibratory plate and, in addition, the most dorsal com- 

 ponent of the adductor muscle which attaches above the apodeme joining the d and 

 e sclerites. Postero-laterally there arise the nerves to the second trunk limbs. Dorsally, 

 at the morphologically posterior end, there is an irregular connection to a group of 

 nerve cells in the caudal furca, but I have not been able to follow the details in this 

 region with certainty. 



The nerves which I have described have been figured by Liiders in Gigantocypris 

 in the same relative positions, with the exception of the three largest, the adductor 

 muscle nerve and the anterior and posterior valve nerves, 



BASAL GANGLION SYSTEM 



The nervous system of Doloria is peculiar in that each segmental nerve swells out 

 into a ganglion in the base of the limb it supplies. These ganglia I call the basal ganglia. 



A ganglion at the base of the antennule has been described in many Crustacea. 

 A ganglion in the base of the antenna is figured by Claus in Halocyprids (1891, Plate i), 

 and Liiders (1909, p. 136) mentions a basal ganghon occurring in the fused bases of 

 the first trunk limbs (his second thoracic limb), but these authors do not comment 

 upon the occurrence of these ganglia. So far as I am aware no Crustacean has been 

 described with basal ganglia in all its limbs. 



From sections of Gigantocypris, also collected by the Discovery expedition, I find 

 that a similar series of gangha occurs in this form, but I have not yet examined the 

 sections in detail. 



The antennulary basal ganglion is the largest in the body, occupying most of the 

 basal joint. Certain fibres pass directly through the ganglion to the muscles (Fig. 10 A). 

 These probably represent the motor nerves, and may correspond to one of the pair of 

 nerves in those forms where antennulary nerves with double roots have been described 

 (Hanstrom, 1924, Figs. 1,2). Other fibres on entering the ganglion from the antennulary 

 nerve turn sharply inwards, and appear to terminate in cells in the postero-medial 

 corner of the ganglion. From this region other fibres extend to the distal end of the 



