313 



(2) The two fang-like cheliceres lying loosely 

 each in a sheath above the horizontal plate and nearly 

 filling the upper cavity of the rostrum. 



(3) A triradiate pumping organ (pharynx) lying 

 below the horizontal plate and occupying, with its 

 muscles, the lower cavity of the rostrum. 



(B) EURHIPICEPHALUS 



The Gorged Female. Obtain a large gravid female 

 and remove the dorsal chitin, as in Ornithodoros, but 

 avoid cutting through the rostrum. Observe that, in 

 the main, the organs are similar to those of Omithodoros, 

 but that the following differences are present (Fig. 

 lOl) : 



(a) The system of diverticula is simpler, and 

 there are no anterior branches. 



(b) The ovary is much longer and thinner, and 

 the spermatheca relatively much smaller. 



(c) The salivary acini are much more loosely 

 packed so that the organ, as a whole, is less easily 

 differentiated. 



(d) The cephalic gland consists of a number of 

 long finger-like projections. 



(e) There are large dermal glands lying among 

 the fat and tracheal tissue. 



The Ungorged Female. Place on a slide and with 

 a sharp knife bisect the tick along the middle line. 

 Place one of the halves in a drop of saline, and fixing the 

 extreme outer edge by means of a needle, scoop out 

 the whole of the contents with a scalpel, disturbing 

 the arrangement of the tissues as little as possible. 

 Under a lens most of the viscera are readily isolated and 

 can be removed for study to another drop of saline. 



