278 ENTOMOLOGICAL SOCIETY 



The basal joint is distinct, though small, ring-like, and shorter 

 than broad. It is by its free situation on a sloping base that the 

 palpi are enabled to move in a perfectly horizontal position, when 

 the rostrum is introduced to its full length into the skin of the 

 host. The second joint is often blended together with the third 

 into one large part, but a dividing line is always visible. The 

 second joint has its upper side at the base sometimes drawn out 

 into an angle which reaches over the first joint and gives it a 

 somewhat triangular aspect. In another instance this joint is at 

 its base drawn out latterly into a sharp and prominent point 

 (Rhiplstoma}. Sometimes this projection at the base is rounded 

 (JFicemapkysalis), or the second and third joints have each at their 

 base a prominent rim which reaches externally over the edge of 

 the joint {Boophilus} . The third joint is generally shorter than 

 the second, but sometimes a little broader (Amblyomma}, giving 

 the palpus a clavate appearance. In some instances, however, it 

 is narrower. The second and third joints are always excavated 

 or canaliculated longitudinally at their inner side so that the palpi 

 can enclose the sides of the rostrum and form a projecting sheath 

 for that organ. The fourth joint is a very peculiar one in regard 

 to its form and position and was for a long time misunderstood. 

 Koch says that the three-jointed palpi have on the last joint an 

 orifice which is closed by a membrane, that serves as an olfactorv 

 organ. He had, however, doubtless examined only dead speci 

 mens, for here the fourth joint is retracted in the body of the third, 

 and what Koch considered a membrane is in reality the apex of 

 the fourth joint. This terminal joint is not visible from the dor 

 sal view, for it is inserted on the underside and at the inner edge 

 of the third articulation ; it is very small and more slender than 

 any of the other joints and can not only be projected and retracted, 

 but moved at will in all directions with astonishing rapidity 

 against the slightly projecting outer edge of the base, like a thumb 

 against the hand. 



The Body : In describing the morphological features of the 

 body I deem it necessary to consider this part separately in the 

 two conditions of the Tick, the free-living' and the parasitic states. 

 The former will be considered first and the three stages of devel 

 opment treated separately. 



The young, newly-hatched Tick presents in its first or larval 



