446 



Avery E. Lambert. 



The conditions which obtain in the development and structure of 

 the brain of the Epeiroid spiders fulfil the conditions of this descrip- 



Text- 

 above. 

 nerve, 

 mental 

 nerves 

 (supra- 

 ganglia 



Figure 2. Brain of the Epeiroid spider, Argiope riparia, viewed from 

 n. ol — n. o2, optic nerves supplying the median eyes. cl\. n., cheliceral 

 md. n., mandibular nerve, n. pd., pedipalpal nerve, ml — mlO, seg- 

 nerves supplying the muscles and the body wall. n. a pi — n. ap4, 

 to the thoracic appendages, v. c, nerve cord. o. h, optic lobes 

 oesophageal brain mass), ocs., oesophagus, .s-. o. //., sub-cesophageal 



tion perfectly. The commissures which St. Remy found uniting the 

 lateral portions of the procephalic lobes, are present in the earlier 

 stages of the brain as the supra- and sub-oesophageal commissures. 



