R. T. LEWIS ON IXODES REBUTIi'S (lINX.). 385 



Journal for 1892, (vol. v., plate 1,) and both the inner and 

 outer mandibles of each pair are jointed upon their rec?pective 

 shafts, so as to allow of a movement through an arc of about 90^ 

 from the median line. In mounted specimens these sheaths appear 

 to be rigid structures. In dried specimens they are thin, hard, 

 and brittle, but in the Living tick they are seen to be pliable, 

 elastic and capable of free and independent retraction ; the shafts 

 of the mandibles being withdrawn within the body of the tick, the 

 blades remain exposed as before, but the sheaths themselves 

 shorten until they disappear by a process of invagination after the 

 manner in which a snail draws in its tentacles. The labium, as 

 seen from its ventral aspect, presents distinctly different features 

 in the two sexes. In the female (Fig. 2) its margin is armed on 

 either side with a row of extremely hard, sharp, arrow-pointed teeth, 

 eleven or twelve in number, increasing in size and strength from 

 the extremity to about half-way down, thence diminishing again 

 towards the base. The convex under surface of the labium is 

 also set with reflexed teeth, three rows on either side of the median 

 line — those near the tip being small and crowded together — but 

 increasing in size in about the same ratio as the marginal rows^ 

 and becoming sparse and disappearing about the same distance 

 from the base. In the case of the male (Fig. i) the labium is 

 shorter ; the marginal teeth are five or six in number and 

 abruptly end with the largest of the series at rather less than 

 half the distance between the anterior extremity and the base, 

 the teeth upon the ventral surface being few in number and 

 projecting so slightlv as to be little more than crenulations. A 

 little below the position of the last of the marginal teeth there 

 are, however, what appear in a dry specimen to be two reflexed 

 teeth, one on either side of the median line, these being of larger 

 size, thicker at the base and longer but not so sharp, and differing- 

 also in apparent structure from any others of theii* kind. On 

 forcibly separating a male from a female and examining the 

 rostrum of the former immecUately after its withdrawal from the 

 vulva, I saw at once that these supposed teeth had increased in 

 size and now presented the appearance of flexible semi-transparent 

 tubular papillae, which conveyed the impression to mv mind that 

 here, possibly, were the organs by means of which the actual 

 impregnation took place. I killed this tick without loss of time, 

 and removing the entii-e capitulum before it had time to drv or 

 contract, mounted it forthwith in glycerine. As thus mounted 



