NERVOUS SYSTEM OF SCORPION. 



53 



haemal" nerve of the same neuromere. What he calls the "an- 

 terior haemal " nerve is another branch of the pedipalp nerve. 

 I have carefully studied the nerves in the region where he de- 

 scribed the ganglion (Fig. 12, 3/ 31 ) but have been unable to find 

 the ganglion. 



The nerves to the thoracic appendages and the pectines are 

 larger, and arise from a more ventral part of the cephala-thoracic 

 nerve mass than the other nerves and are classed by Patten as 

 " neural' nerves. Fig. 12 shows how I have classified these 

 nerves from a study of their development better than a description 

 would do. In Fig. 1 1 I have shown that neuromeres eleven to 



FIG. 13. Tenth stage (adult), X 34- Median sagittal section of cephalothoracic 

 nerve mass. ii l ~ n , first to eleventh neuromeres; J?, rostral nerve; st, stratified 

 organ of Saint- Remy ; w, blood vessels between the neuromeres. 



twenty innervate not only their corresponding segments, but each 

 sends nerves to muscles lying in the succeeding segment. It is 

 possible that the myomeres as well as the nerves are displaced 

 somewhat backward. Patten claims that in the scorpion some 

 nerves wander to segments to which they did not originally 

 belong, and describes certain nerves (Fig. 12, gA, gP, loA, i lA, 

 i iP] as "vagus" nerves. Police (1901, i) denies that this is 

 true, and with the exception stated above, it is not true accord- 

 ing to my observations. 



