Terminal Organ of the Pedipalp ofGalcodes c&c. 29 



attention. Dufoiiv * himself assumed that it was a sucker- 

 like seizing-organ, and this view has again been expressed 

 quite recently f. 



A close examination of it shows almost conclusively that 

 Koch's \ suggestion that it is a sensory organ, probably 

 olfactory, is correct. 



We may at the outset remark, first, that such a minute and 

 delicate seizing-organ in an animal armed like Galeodes 

 would be ridiculously out of proportion, and, secondly, that a 

 highly specialized sensory organ might be expected in such 

 swift runners who hunt their prey. 



The organ itself is essentially an invagination of the tip of 

 the pedipalp, forming a conical pit, the thin chitinous walls 

 of which are continued into the metatarsus as a tendon to 

 which a powerful muscle is attached. The external aperture 

 of the pit is a transverse slit, which closes like a pair of lips. 

 The upper lip, i. e, that on the dorsal or outer side of the 

 limb, is stiff and solid, and is opened by means of a long 

 tendon connecting it with a muscle far down in the meta- 

 tarsus. The opening of this lip like a lid leads apparently to 

 the slight protrusion of the organ, ^". e. by drawing it up with 

 it. I could find no other mechanism to explain it. 



Within the pit one wall only, i. e. the dorsal, is thickly 

 covered with fine sensory hairs, so regularly arranged that 

 the chitinous membrane from which they arise appears like a 

 fine network. The hairs are in evident connexion with a 

 deep sensory epithelium immediately under the chitinous 

 membrane. This epithelium runs a long way down the 

 (hollow ?) tendon. The ventral wall of the pit is an exceed- 

 ingly fine chitinous membrane, against which, when the 

 aperture is closed, the tips of the hairs apparently rest. 



If this is not enough to show that this organ is not a seizing 

 but a sensory organ, the discovery of a very similar organ in 

 the pedipalps of Phrynus on the inner surface of the most 

 distal claw effectually settles the question. In the adult 

 specimens a sensory area runs longitudinally from the joint 

 along about half the length of the claw ; but I was unable to 

 discover any chitinous invagination. In a young specimen, 

 however, which could be clarified, an invagination of this 

 same area was very clear. It occurred on the dorsal side of 



* Dufour, " Anatomie, histologie, et pliysiologie naturelle des Galeodes^ 

 Memoires presentees a I'Institut de France, vol. xvii. 



t Bertkau, " Ueber Sinnesorgane in den Tastern imd in den ersten 

 Beinpaar der Solpugiden," Zool. Anz., Jan. 1892, 



X Koch, " Systematische Uebersicht iiber die Familien der Galeoden," 

 Archiv fiir Naturgescb., 1842 . 



