362 HENRY SHIMER, M. D. 



they drag over the slide, are seen greatly to impede their motion, on 

 account of the precipitation of a very slight film or moisture on the 

 slide. Six short spines are seen to project from the forehead, and 

 many all around the body. Feet one-jointed. Two finger-like organs. 

 — digituli — (^Proc. Acad. Nat. Sciences, Phil., Jan. 1867,) are readily 

 seen projecting beyond the extremity of the tarsi, with enlarged extre- 

 mities, but which are not globular, as in the Dacti/losphseridee. These 

 extremities appear much like arolia ov pulvilli, which I am convinced 

 they are, from various observations. 



But upon a closer examination of the feet, we find four of these di- 

 gituli, the upper pair being apparently longer, as seen from above, the 

 under pair is set somewhat farther back on the tarsi beneath, and usu- 

 ally, when walking, both these lower digituli are directed forward to 

 aid in locomotion, when they appear bent forward; sometimes, how- 

 ever, when the leg was not in vigorous motion, or when it was injured 

 somewhat, I saw them closed on the foot beneath, very much like the 

 thumb in the palm of the hand; and then the movements of the insect 

 were very awkward, manifestly lame. I have frequently seen under 

 close examination, with a one-twelfth inch objective, that the insect, 

 when walking naturally and in possession of its full powers of locomo- 

 tion, invariably projects the two inferior digituli obliquely forward, and 

 that it supports its weight upon them ; the upper digituli frequently 

 bend into quite a curve in walking, thus proving that they are corea- 

 ceous or membranaceous, and not corneous. 



These digituli are, without doubt, of the same material as the leg. 

 llepeating my examinations of these tarsal organs, on the following 

 days, I have noted that the tarsal segment is very short, almost incon- 

 spicuous as to its separation from the tibia; the digituli almost appear 

 to sprout out of the lower end of the tibia, so short and undeveloped 

 does the tarsal segment appear under the microscope. 



In form, all the digituli are somewhat tapering towards the distal 

 end, and terminated by an enlargement or disk ; the two digituli be- 

 neath present the most conspicuous disks, which, under the micrcosope, 

 appear blackish. The lower digituli are invariably directed forward 

 when the insect walks. This bending forward is caused by the mus- 

 cular exertion of the insect as it pushes its body onward, giving there- 

 by, sufficient backward pressure on the foot to make the digituli, on 

 which its weight is sustained, to bend forward as already described. 



This pi'oves two things : — 1st. That these organs beneath are true 

 digituli, or organs, at all events, that are sufficiently pliable to bend 



