found on the Head of a Bat. 147 



neiglibouring parts from slight compression, almost prevent the 

 possibility of assigning to each the proper position ; while in the 

 natural state, being often covered with exudation from the wound 

 and filled with dense grumous matter, exactitude in the description 

 is by no means easy. At Fig. 3 is given the ventral aspect of 

 another insect and the mode of attachment of the legs : one, the 

 hind leg, is shown at Fig. 6 ; it is furnished with numerous stiff 

 and branched hairs ; the tarsus, which is longer than in the other 

 legs, terminates, as each one does, in three claws, the outer two 

 uncinae being expanded, stronger, and more curved than the middle 

 or long one. The ventral aperture is shown in Fig. 4. In Fig. 5 

 is depicted a portion of the dermic tissue of the saccular body, dupli- 

 cated at one part, and also showing the inner surface, to which can 

 be seen attached five (?) muscular bands,* stretching between the 

 surfaces. No transverse striae were seen on these bands, but they 

 are supposed to be muscular in action. 



Tliis description difiers in several particulars from the small 

 hexapod mite, 1 mm. in length, the Argas pipisti'ell^, found 

 attached to the body of the bat, and described by Lucas in his 

 ' Cours Complet d'Histoire Naturelle,' tome xiii., p. 483, but bor- 

 rowed from M. Audouin's observations, the tarsi terminating in 

 two small hooks, &c. Not finding any satisfactory description of 

 this insect I felt much puzzled whether these mites should be 

 considered as belonging to the " degraded diptera," or whether they 

 were merely the larval form of some psoreptes, or itch mite. 

 Accordingly, considerable time was spent in looking for more 

 advanced specimens, as the whole of those grouped together 

 appeared to belong to only one sex, and were possibly the early 

 stage of some well-known form. After much patience I was 

 rewarded by finding among the hairs, one, and only one specimen, 

 very much smaller, difiering greatly in appearance from the rest, 

 and approaching more nearly the character of the male itch insect. 

 Yet on higher magnifying, it was seen to differ considerably {vide 

 Fig, 9). Its size is about 165th of an inch. The dermic tissue is 

 plain, or shows no transverse lines. Six of the legs are provided 

 with a small disk ; the other two of the hind legs (for in all they are 

 eight in number) consist apparently of two long joints, one being 

 setigerous ; their position, distant from the anterior pairs, is similar 

 to the itch mite — possibly an immature male — though in the male 

 itch insects I have examined, if I remember correctly, the outer 

 hind legs are provided with bristles, the inner with disks, which is 

 the reverse in the insect under consideration. Looking at these 

 points, and not knowing whether the single insect had any relation 

 to the rest, under present cu'cumstances it will, it is thought, be 

 better to leave the matter open, as to their position in the family 

 of Arachnidae. 



