A NEW SPECIES OF PHASMIDiG. 53 



in such a situation, and we can see also that the so-called 

 claspers on the abdomen, the knee-pans, the fringes of hair, the 

 dentate margins of the legs, &c., are only so many further 

 adaptations, all of which lend themselves obviously to the same 

 purpose of concealment. The under side of the insect's body is 

 smooth and polished, and of a reddish-brown colour marked a 

 little with black ; but that is just the part which, when the insect 

 is at rest, cannot be seen. That it should act like a sucker, 

 seems a physical impossibility ; and one needs only to examine 

 the insect awhile to see how absurd is all the talk about the 

 imperviousness to water of its various structures. 



As evidence, therefore, of the aquatic habits of Prisopus, all 

 the wealth of " corroborative detail " supplied by Murray must 

 be regarded as absolutely valueless, although, no doubt, it did 

 succeed in giving " artistic verisimilitude to a bald and un- 

 convincing narrative," and must have exercised a strong influence 

 on the judgment of subsequent writers, who, without it, we may 

 be well persuaded, would not for a moment have given credit to 

 a story so highly improbable, so utterly opposed to everything 

 known about the habits of the Phasmidee, 



Wood-Mason, well known as an authority on the morphology 

 of insects, was one of those who fully accepted Murray's account 

 of the habits of Prisopus ; and when his attention was called 

 to another Phasmid, apparently closely related to that genus 

 and distinguished by having a row of five flat oval, fringed 

 structures attached to each side of the metathorax, he at once 

 jumped to the conclusion that these structures were tracheal 

 gills, and he has described them as such, giving to the insect the 

 name of Cotylosoma dipneusticum. " This insect," he writes, 

 " is closely related to the Prisopi, but is even more profoundly 

 modified for an aquatic life ; for it breathes, not only in the 

 ordinary fashion amongst insects by means of tracheae opening 

 by stigmata to the exterior of the body, but also by the structures 

 known as tracheal gills." His statement seems to have passed 

 unchallenged until, in 1895, both Dr. Sharp and Mr. C. 0. 

 Waterhouse called attention to it, and expressed their doubts 

 about the function attributed to the so-called tracheal gills. 

 The question, however, as to the true nature of the structures 

 was left undecided. Having examined them lately, I have come 

 to the conclusion that they cannot possibly be tracheal gills. In 

 the first place, they exhibit no traces whatever of tracheae, and, 

 secondly, they are dotted all over with dark pigment spots. 

 They are to a certain extent movable, and they are in form and 

 structure, as Waterhouse has pointed out, very like the two flat 

 oval appendages at the base of the front tibiae in Prisopus, the 

 so-called " knee-pans " described by Murray. And it appears to 

 me that their purpose is the same — to effect the better con- 

 cealment of a part which, without them, would be somewhat too 



