44 SELECTED NOTES FROM 



underneath them. These movements I suppose to be effected 

 by thoracic muscles, and by the mechanical action of puUing 

 the wing backwards (like closing a fan). The folding of the tip, 

 I judge, is caused by the natural elasticity of the wing, and it is 

 unfolded when the beetle expands its wings, by the tightening of 

 a tendon that runs down inside the sub-costal vein. This is 

 shown by a line (much too thick) in Figs, i and 2, and of its 

 (comparative) proper size in Fig. 4. I fancy that a " round-the- 

 corner" pull of ithis, at the end of the sub-costal vein, would 

 unfold the tip. The dark colour of the wing in places is caused 

 by numerous fine hairs, shown at Fig. 3. 



The great nervures are hollow, and down each one a trachea 

 (Fig. 4.) runs. The smaller nervures seem solid. On the upper 

 side of the sub-costal nervure, close to its base, are two groups of 

 the curious organs supposed to be "otoconia." They are on the 

 surface of the nervure, and are highly refractive of light. They 

 appear to be seated on globular cells within the nervure. 

 AVhether they really be organs of hearing, I am unable to say : 

 perhaps some of our members can throw some light on this 

 interesting question. I have found them in every wing that I 

 have investigated, except the May-flies, but they are not always 

 on the sub-costal vein ; in the bees they are on one of the joints 

 at the base of the wing. 



H. M. J. Underhill. 



DESCRIPTION OF PLATE IV. 



Upper portion : — mouth dissected and viewed from above. 

 l.h.r., Labrum or upper-lip. 

 m.d. Mandibles. 



m.x., Maxilla3 ; m.i?., Maxillary palpi. 

 La,, Labium, or lower-lip ; l.j)., l.j)., Labial palpi ; m.t, Mentum or 



chin. 

 Lower jDortion : — 



Fig. 1. — Left wing folded ; c.o., Costal ; s.c, Sub-costal ; r., Radia ; 



C.U., Cubital nervures ; s.c, is the tendon which folds the tip. 

 Fig. 2. — Right wing spread out. 

 Fig. 3. — Group of hairs which give the brown part of the wing their 



tint. 

 Fig. 4. — Small portion of the sub-costal nervure, near its base, upper 



side showing i.r., a Trachea; i.e., the Tendon, marked s.c. in 



Fifr. 1 



Gamasus, from Humble-Bee (PI. 2, lower half).— These 

 may be found frequently in hundreds on Humble-Bees, but I 

 do not remember ever to have seen them on any other kind of 



