no A. D. MICHAEL ON TWO SPECIES OF ACARINA. 



distended by eggs ; and many other by no means unimportant 

 points agree with the Gamasiuce. On the other hand, one can 

 scarcely venture to include it in that family in the face of the 

 following differences, viz., firstly, the mandibles are not retractile ; 

 whereas in all Gamasinoe which I know of they can be wholly 

 retracted within the body, often so far that it is quite startling, and 

 this forms a leading character. Secondly, the genital opening is on 

 the abdomen close to the anus instead of in the cephalothorax as in 

 Gamasince. Thirdly, the anus is protected by plates differing 

 greatly from the Gamasince. Fourthly, the palpi have four joints ; 

 Gamasince have five. Fifthly, the tarsus is not provided with a 

 caroncle. Sixthly, the joining of the segments of the sternum by 

 apodemes above referred to is not found in the Gamasince. 



DESCRirTION. 



Adult. {Plate VI, Fig. 2.) 



^ Average length about . . . . -68 mm. 



„ breadth „ .... -36 mm. 

 „ length of legs, 1st and 4th pairs 



about '45 mm. 



,, length of legs, 2nd and 3rd pairs 



about ..... '32 mm. 



The whole creature is chitinous and of a beautiful orange, and 

 appears divided into three parts ; the anterior of these, which is far 

 the smallest, is really the rostrum and mouth organs, of which the 

 enormous mandibles almost hide all the rest ; the second is the 

 remainder of the cephalothorax ; and the third, and far the largest, 

 is the abdomen. The whole dorsal surface is reticulated with 

 raised ridges enclosing sj^aces most commonly hexagonal, but very 

 frequently pentagonal and of other forms ; all the ridges are marked 

 with regular depressed transverse striae, giving them a beautifully 

 finished appearance (Plate VI, Figs. 2 and 8). 



The rostrum, as seen from above, would appear to consist of the 

 mandibles only (Figs. 1 and 2, and Fig. 4), as they arise imme- 

 diately from the camerostomium, and from their great size hide the 

 whole of the rest of the organs ; their full length (as seen from 

 below) is more than a quarter of that of the creature, but only about 

 half is seen from above. Each mandible is thin, narrow, and of 



