R. T. LEWIS ON A SPECIES OF IXODES. 13 



it is seen that tlie line of fusion is not equally well marked above 

 and below, but that whereas a slight groove only remains upon 

 the upper surface, there is one of considerably greater depth 

 and breadth below. A pair of palpi arise from the ventral sur- 

 face of the head adjacent to the base of the labium ; these are 

 four-jointed, the second joint being considerably longer than the 

 others, and the fourth (scarcely discernible in a dried specimen) 

 is furnished with a circular tuft of apparently sensory hairs. 



One of the characters of the genus Ixodes, given by Van der 

 Hoeven and others, is " palpi sheathing the rostrum," which 

 these can scarcely be said to do, although in a large specimen 

 of cattle tick, still alive in my possession, I notice that these 

 palpi are, when at rest, brought up close to the sheath, and that 

 the terminal joints are bent towards each other as if to afford 

 additional protection to the apices of the mandibles. In every 

 species yet examined the whole rostrum is capable of being 

 moved through an angle of at least 90° from the horizontal 

 downwards by the elevation or depression of the head. It will 

 be seen from Fig, 4 that the labium, as viewed from its under 

 side, contracts in breadth from its base for about half its length, 

 thence expanding again, but at the same time diminishing in 

 thickness so as to resemble in shape the convex side of the 

 bowl of an ordinary bone egg-spoon. The part nearest to the 

 base is ribbed, and has the appearance of possessing great 

 rigidity and strength, whilst the spoon-shaped portion is set 

 with six rows of triangular barbs, seven in each row, and all 

 pointing downwards and backw^ards, at an angle of about 35°. 



The structure of the lacinia — or mandibles, as most authorities 

 term them — is not so easily made out ; but repeated examina- 

 tions of each available specimen in many different ways, and a 

 comparison with an allied form found upon a tortoise, lead to 

 the conclusion that there are two pairs, which differ in shape, 

 and are capable of independent movement within a radius at 

 least equal to the semi- diameter of the rostrum. The outer pair 

 (Fig. 7) are nearly flat, the apex being smooth at the back, but 

 furnished on the opposite margin with three lancet-shaped 

 teeth, pointing outwards, and apparently sharp on both edges, 

 so as to cut equally well with a backward or forward thrust. 

 The inner pair (Fig. 6) are more peculiar in shape, the shaft 

 being deeply hollowed like the blade of a gouge, expanding to- 



