670 MEDICAL ENTOMOLOGY 



in shape. The hairs which pierce the skin are distributed somewhat 

 irregularly over the body, and lie in cups just below the surface ; the cups 

 are continuous with small canals which pass through the chitinous 

 layer to the cellular. 



The inner surface of the integument serves for the attachment of 

 muscles, which are arranged in groups and which divide the haemato- 



coele into several compartments ; the most prominent 

 The Muscular System *, 



are those which run across the body from the dorsal 



to the ventral surface. One set arises from the scutum on each side 

 of the middle line and passes downwards and backwards to be inserted 

 on the ventral integument ; another set arises on each side at the junction 

 of the middle and posterior thirds of the body and passes downwards to 

 the region of the anus. The origins and insertions of these muscles in the 

 integument produce the characteristic furrows seen on the outer surface. 

 A large band of muscles arises from the ventral surface of the scutum 

 and from the integument in the neighbourhood of the fourth pair of legs 

 and passes forwards and upwards to be inserted into the bulbs of the 

 mandibles ; these are evidently the retractors of the mandibles. Another 

 set passes from the under surface of the capitulum and is inserted into the 

 bulbs of the mandibles ; these by pulling on the mandibles would protract 

 them. There are also other bands of muscles which pass from the 

 scutum to the mouth ring and are probably brought into play in tilting 

 the mouth parts, a movement which is seen during the act of feeding, 

 and also when the female is about to oviposit. 



In considering the structure of the female reproductive organs it is 



necessary to describe first their appearance in the unfed, unimpregnated 



female, for the conditions change when the female at- 



Svstem The female tacnes itself to the host and is impregnated. The ovary } 



organs in the unim- which is quite unlike that of the Insecta, is a single 



pregnated condition, hollow organ, and lies in a somewhat oblique direction 



Plates LXXXili and ,, , , u u , ,, , r ,1 i , , i 



LXXXIV across the body, behind the end ot the mid-intestine, and 



above the posterior diverticula. Its dorsal surface is in 

 close contact with connective tissue, fat body, loops of Malpighian tubes 

 and the posterior part of the heart. In the Argatini the ovary is short 

 and broad, while in the Ixodini it is U-shaped (Plate LXXXIV, figs. 2 

 and 5), and is often extremely long and narrow, filling up the posterior 

 part of the body. In the unimpregnated condition it consists of unripe 

 ova which may be recognized by their shining brown appearance ; each 

 ovum contains a large quantity of yelk and is loosely attached to a 

 delicate membrane. The ova appear to be formed only on the dorsal 



