Ill 



and if the frass should be matted together by being wetted, the burrow oftfili 

 extends through it to the surface, occasionally forming a tubular addition td 

 the burrow of an inch or more in length ; but this is a purely accidental occur- 

 rence. 



I had the good fortune on one occasion to observe the process of sepa- 

 rating this splintery variety of frass. I had so split a piece of wood as to 

 expose a burrow within a few lines of its inner extremity. In this burrow was 

 a beetle that could not, in these circumstances, completely hide itself. It con- 

 tinued, however, to work, and kept ejecting frass of this description. It moved 

 very gently, as beetles do when moving their jaws, with the exception that 

 every ten seconds it came out with a sudden jerk for a distance equal to one- 

 third its own length, so one could not help concluding that something it was 

 pulling at had suddenly given way. I think that I am justified in inferring from 

 this that these little splinters are bitten through at one or both ends, and 

 then laid hold of and separated by a pull ending in the sudden jerk resulting 

 from the bit of wood becoming loose. 



I may mention that, when perfect, P. Cylindrus has very long slender 

 tarsi, and that it is a matter of notoriety among collectors that it is usually 

 met with having these broken. This is almost invariably the case with those 

 beetles that have formed a burrow ; they often possess no tarsi whatever, except 

 about half of the basal joints. It occurred to me that this sudden jerk suffi- 

 ciently explained this want of tarsi. Such a beetle when extracted from his bur- 

 row is utterly helpless, yet in this state he manages to run backwards and for- 

 wards in his burrow with great facility, to live there in apparent health for 

 many months, and as he never naturally leaves the burrow again, the loss must 

 be of but little consequence. The newly-emerged beetles, that is, those pos- 

 sessing their long and delicate tarsi, do not seem comfortable on a smooth 

 surface, but over a rough piece of bark they can run with great agility. I sus- 

 pect, though on this point I have made no observations, that they find them very 

 useful in sustaining the body in a proper position at right angles to the surface 

 of the wood or bark in commencing their burrows. As to the mechanism of 

 this jerk by which the splinters are separated, the anterior femora of Platypus 

 (6 TzKarvq ttovq) are extremely broad, or rather deep, from which circumstance 

 indeed the genus is named ; and are not by any means narrowed in the other 

 diameter to make amends, but are really extremely strong limbs ; the anterior 

 tibice are, externally, diagonally ridged, but in such a way that though the 

 ridges are diagonal to the tibia, they are, when it is in its usual position, 

 transverse to the burrow, and are sharpest forwards, so that they must give 

 a very firm hold of the wall of the burrow when the beetle uses his strong 

 femoral muscles to push himself backwards. 



Although the jaws are, as usual, directed forwards, their sharp, cutting 

 edges are quite in advance of the beetle, when the head is in its normal posi- 

 tion, and are thus beautifullv nrinutprl for cutting- thn wood round the side of 



