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



scription of them is unfortunately beset with difficulties, re- 

 quiring, as it would for its completion, the examination of many- 

 specimens, living as well as dead, together with dissections and 

 preparations, for which the present supply is entirely inade- 

 quate ; added to this, each independent writer upon the subject 

 seems to have adopted a different view as to the homologies of 

 the parts, resulting in many synonyms and a confusion of nomen- 

 clature, which, to say the least, is a little bewildering. 



The most, therefore, that I can hope to do on this occasion is 

 to describe the appearance presented by such portions as are 

 visible in the dried specimens, which at least have the advan- 

 tage of being unaltered in shape or relative position by any 

 processes of preparation or pressure in mounting. 



I am, however, much indebted to my friend, Mr. Thomas 

 Curties, for kindly placing at my disposal for purposes of com- 

 parison some excellent slides of various ticks, which have been 

 of material assistance in tracing their analogies. The rostrum, 

 as seen in profile (Fig. 2), consists mainly of two parts, separ- 

 able from each other, but with their adjacent surfaces so true 

 as to admit of the closest contact between their outer edges. 

 Of these the lower, or ventral portion, is commonly termed 

 the labium. The upper portion, which is slightly longer than 

 the labium, is bevelled off downwards near to the apex, from 

 which the ends of two pairs of cutting instruments are seen to 

 project. Viewed from above (Fig. 3), it gives the impression 

 of being formed of two parallel tubes, '55 m.m. in length, with 

 a combined breadth of "2 m.m., laid side by side, and fused 

 together along the line of contact ; certain it is that they are 

 tubular throughout, and that one purpose which they serve is 

 that of a protecting sheath to the cutting tools or mandibles 

 within. Specimens of allied species, prepared so as to be almost 

 translucent, and mounted in balsam, show the mandibles 

 passing freely through, and enable them to be clearly traced 

 backwards to their muscular attachments behind the head. A 

 well-marked median suture suggests the idea that these sheaths 

 were at one time separate ; but experiment shows them to be so 

 no longer, although they have in one or two mounted specimens 

 become so, as the result of maceration and flattening under pres- 

 sure. 



"When looked at "-end on " (Fig. 5), or in transverse section, 



