Boijal Microscopical Society. 243 



course no covering glass. This required some management, as 

 when quite wet the object would present only a glare of light, and 

 when dry the parts would be shrivelled ; but by carefully choosing 

 the proper moment when surface evaporation had taken place, a 

 very satisfactory view could be got with a Ath objective, but many 

 a hundred coaxings were necessary to get the parts into definite 

 positions ere I could satisfy myself of the arrangement of what I 

 will venture to call the " suckers" attached to the pseudo-trachefe of 

 Diptera ; for, so far as I have been able to make out, there is a certain 

 identity of arrangement for suctorial purposes in the tongues of all 

 the so-called flies, though the shape of the lobes and the arrange- 

 ment of the teeth may and do differ very materially. 



The general appearance and arrangement of the pseudo-tracheae, 

 I take it, are well known to microscopists ; these quasi-tubes have 

 been called " probosces," from a certain resemblance they have to 

 the trunk of the elephant ; but if I am correct in my observations, 

 these insect probosces have the advantage over the animal, in that 

 they can take in fluid not only at the distal ends, but also, at the 

 will of the creature, along the whole length of the tube. If we 

 look carefully at a tube or proboscis, we shall find down the said 

 whole length a zigzag slit or furrow, which is kept open by a series 

 of incomplete chitiuous rings, first described, I believe, by my friend 

 Mr. George Hunt, each incomplete ring having at the ends a quasi- 

 point and a crescent, which are opposite to each other, and form the 

 framework of the fissure; and the point clothed with investing 

 membranes projecting opposite to the hollow of the crescent gives 

 the zigzag effect, which can easily be seen on examining by reflected 

 Hght the lobes of the tongue of a freshly-killed fly. At the same 

 time, it will be observed that these pseudo- trachea are imbedded in 

 the substance of the fleshy lobe, so that the edges of the fissure, and 

 the " ear-like " appendages I am about to describe, project but little 

 above the general surface of the lobe. I call these ''ear-hke" 

 appendages, because in certain profile views of a pseudo -trachea — 

 and particularly when the object has been squeezed down and 

 deformed — a couple of ear-like bodies will be apparent as in some 

 way connected with the crescentic end of the chitinous ring or 

 arch. Now, seen with as httle disturbance of the parts as may 

 be, and viewed directly in front, the membranes which form this 

 spurious appearance of " mouse's ears " or " bat's ears," will be seen 

 to be arranged as I have drawn them in Fig. 1, each membrane 

 attached round the edges of the crescents in a way that will be 

 more readily understood by an inspection of Fig. 2, where the parts 

 are seen in profile, a copy of an existing preparation, one out of 

 many dissections, where, by cleaning away the matter, whatever 

 that may be, from the back of the lobe, and by careful tilting, the 

 fragment of the tube has been got into the position the pseudo- 



