HANSEN: EXTERNAL SENSORY ORGANS IN ARACHNIDA. 247 



the upper surface near the end a downwards bent process, 

 »processus terminalis>' W. S., which at least as a rule has 

 a couple of long, slightly curved sensory hairs; in the lamiiy 

 Assamoidae, which has no »processus terminalis», a very short, 

 thick sensory seta is found on the upper side of the tarsus 

 near the end. 



Among the suborder Palpatores forms of both tribes, 

 viz. Eupnoi «. J. H. & W. S., and Dyspnoi H. J. H. & 

 W. S., have been examined. Sensory hairs of the somewhat 

 elongate type similar to those in the Cyphophthalmi are 

 found on the tarsus of all pairs of legs, many more on the 

 two anterior than on the two posterior pairs, and in genera 

 with many tarsal joints they are only found on the more 

 distal joints. Besides one or some conical, thick and short 

 sensory set?e are found at least at the distal extremity of 

 the tarsus. 



Before leaving the Opiliones it may be mentioned that 

 most peculiar hairs of very compound structure and unknown 

 function are found on the more distal joints of the palps of 

 Neinastonia lugubre O. F. MÜLL, and in some other species 

 of the same genus. They have been described in 1 893 

 (H. J. Hansen, a, p. 197), and on the same page I described 

 some remarkable bundles of hairs found in the male of 

 Phalangium parietinmn DE Geer on the lower side of the 

 metatarsus and some of the more proximal tarsal joints in 

 the three anterior pairs of legs. 



In the Solifugce I have not been able to discover sen- 

 sory setœ of any kind, but the clothing makes the investi- 

 gation of these animals difficult, and therefore I do not ven- 

 ture absolutely to deny the possibility of the existence of a 

 few sensory hairs in these curious animals. On the Acari I 

 can say very little. In the suborder Notostigmata With in 

 1904 found small and very thin, strongly curved hairs »pla- 

 ced in deep and large articulation cavities» and he considered 

 them to be sensory hairs; they were found »along the dorsal 

 side of the metatarsus of the second, third and fourth pair 

 of legs and ot the outer side of the fourth pair of femurs». — 

 The Oribatidse possess a pair of organs named by MlCHAEL 

 (1884) »pseudostigmata». He described them as »usual 



