46 SELECTED NOTES FROM 



head is a pair of chel^, which are furnished with one moveable 

 joint each, so as to make them into pairs of tweezers. They do 

 not work sideways hke insects' jaws, but up and down. (In 

 Ixodes they are merely serrated lancets and not pincers.) They 

 are capable of considerable extrusion and retraction, but often in 

 mounted specimens they are forced out too far. I imagine that 

 they are analogous to, if not homologous with, the falces of a 

 spider — i.e., they have no connection with the mouth (strictly 

 speaking), but serve merely to hold the food. 



Below the chelae is the mouth. This has a pair of maxilla 

 (?) {mx., Fig. j) ; but I very much doubt if they are moveable, 

 and they certainly do not look as if they could meet. In the 

 middle is a lancet or a rostrum (r) ; this may possibly be hollow. 

 I feel sure that i/iis set of organs, and not the chelae, is the 

 mouth, because the rostrum can be traced to the gullet (g^). If 

 this were all, the mouth would not be difficult to understand, but 

 there is also a most curious fringed tongue (/). I do not ever 

 remember to have seen this figured and described. 



On each side of the mouth is a palpus : the pair form the 

 maxillary palpi. The presence of these palpi is almost universal 

 in insects, arachnida, and myriapoda. Nobody seems to have a 

 very clear idea of their use, but it is generally said that they are 

 for " examining the food," etc. Just below the head of the mite 

 is a little organ with two fringed bristles proceeding from it {s.o., 

 Fig. 2). Perhaps this is a sexual organ. '^ On each side of its 

 base are little thickened plates of chitine. The object of 

 double-staining is to show up the difference in texture of the 

 various parts of the membranous covering of the creature. Thus, 

 the feet are blue and the legs purple, while the membranous 

 joints of the legs and the palpi are blue. Blue and purple, 

 however, do not form by any mea^s a good contrast. 



H. M. J. Underhill. 



DESCRIPTION OF PLATE IL, Lower Half. 



Fig. 1. — Gamasus of Humble-Bee, viewed from above. 

 ,, 2. — Mouth-parts, more highly magnified :c.h., Cheke ; m.p.^ 



Maxillary palpi ; s.o., Organ of unknown function. 

 ,, 3. — Mouth proper, removed : — r.. Rostrum ; t, Tongue 



fringed with hairs ; g.t., Gullet ; m.x. , Maxilla3. 

 ,, 4. — c.Z. , Claw ; p.. Pad. 



Fowl-Mite, Dermanyssus gallinge. — It is very curious 

 how slight the difference is between parasitic and non-para- 

 sitic mites. The difference between parasitic and non-parasitic 



* Mr. Tuffen West thinks there is no reason for assuming this sternal 

 appendage, terminated by two bristles, to be a sexual organ. — \_Ed.'\ 



