116 A. T). MICHAEL ON TWO SPECIES OF ACARINA. 



the sternal surface, and there the rostrum ends in a blunt point. 

 The opening of the mouth is on the under side, and is usually con- 

 cealed by the bending down of the rostrum. The mouth organs are 

 minute and obscure, and appear to consist of two curved style-like 

 mandibles working alternately, and somewhat similar to the trian- 

 gular styles of Mycoptes (which Claparede regarded as the mandible 

 of the Sarcoptidce with the last joint become abortive) and a 

 maxillary lip or maxilla with the palpi almost coalescent with it. 

 The mouth, and probably the first stomach, seem to form a sucking 

 apparatus. 



The cephalothorax on the dorsal surface widens rapidly, so that 

 the fore part of the cephalothorax and the rostrum together form a 

 truncated triangle. The whole length of the under surface of this 

 part of the cephalothorax is occupied by the great round coxa? of 

 the first pair of legs. A little behind these the cephalothorax 

 widens suddenly over the coxas of the second pair of legs, and then 

 sweeps outward until it attains the greatest width over the centre of 

 the coxae of the fourth pair of legs, whence it narrows sharply at 

 the insertion of the abdomen. The posterior angle of the cephalo- 

 thorax projects and forms a shoulder which carries a spine directed 

 backward close to the abdomen and almost reaching its posterior 

 margin. The abdomen is almost square, with the hind corners cut 

 away ; the posterior margin transparent and retractile. 



The anus is small and subterminal, but more on the under than 

 the upper surface. The legs are five-jointed. The coxae of the 

 first three pairs are very large, and look globular. The two first pairs 

 are set in indentations at the side ; the third pair are more under the 

 body, but still at the lateral margin. The fourth pair are entirely 

 different in shape, much longer, set further under the body, thickest, 

 almost straight at the inner edge, shortly afterwards narrowing, 

 becoming tubular, and curving backward and outward. The tro- 

 chanters of the first three pairs of legs are much narrower than the 

 coxae, and seem almost fitted on to the exterior surface thereof. In 

 the third pair in particular the coxae are really indented to receive 

 them. The trochanter is the largest joint, except the tarsus, and, 

 in the third pair, is the longest joint of all. In the fourth pair it 

 is only slightly longer than the coxa. The third joints (femurs) 

 are short and sub-cylindrical in each leg, but slightly wider at the 

 distal extremity. The fourth joint in each leg, except the first, is 

 somewhat similar in shape to the tliird, but nearly twice the length. 



