1916 PoxMONA Journal of Entomology and Zoology, Vol. VIII, No. 2, June 



The Central Nervous System and Simple 

 Reactions of a Rare Whip Scorpion 



WILLIAM A. HILTON 



A number of specimens of Trithyreus pentapeltis Cook were col- 

 lected by the writer in the college park at Claremont. The only 

 other record of any member of this family found in the United 

 States is the early paper of Cook which describes this species from 

 Palm Springs, California. At another time there will be published 

 a description with figures of the general external anatomy of this 

 interesting creature. Fig. 1 is partly from an outline drawing by 

 Miss Margaret Moles. The general position of the nervous system 

 is shown in the outline. So far as we could determine there were 

 no sense organs but hairs. These for the most part were of the 

 usual arthropod type, but there were several modifications of them 

 as will be shown by Miss Moles at a later time. The hairs are 

 most abundant under the body and are probably important organs 

 for giving sensations from the surfaces where the animals run. The 

 most remarkable hair sense organs are on the legs. The figure 

 shows the position of these slender delicate structures, two on the 

 first leg, one on the others. If an animal is approached by any object 

 one of these hairs is apt to be touched, especially if attempts are 

 made to seize the animal. At first it was almost Impossible to be- 

 lieve that the little creatures cild not have eyes, they so well avoided 

 all attempts to capture them with forceps. When approached by 

 some object which probably touches one of the long hairs they run 

 either backwards or forwards apparently with great accuracy de- 

 termining the position of the approaching object. However their 

 backward running is most marked and most remarkable. They run 

 with great swiftness in a backwarci ciirection in some cases for sev- 

 eral inches. I founci little evidence of other sense organs than those 

 of touch. They did not especially avoid strong odors, but after a 

 rather long exposure to strong light or heat they sought refuge under 

 some object. 



Although the chitin is thin in places the first attempts at serial 

 sections through the whole body were not very successful. It was 



