Faunae Subterranece. 145 



Some parts of the structure peculiar to this remarkable animal, 

 demand additional notice, with reference to its mode of existence. 

 On a former occasion* I have pointed out that the organs termed 

 onychia exist more extensively among the Eleutherata than was 

 hitherto supposed to be the case, and that they are found also in 

 Silphidce. They are developed in a peculiar manner in Stagobius, 

 where the proper, horny, basilar-part, is greatly withdrawn, while 

 the two bristles, at its end, are much elongated and directed back- 

 wards, towards the base of the tarsus. There exist, besides, two 

 other setae, equally moveable, but having a forward direction ; 

 these, together with the others, form a cross of four long setae, 

 which constitute the longest of a system of moveable bristles of 

 various lengths ; two pairs being inserted at the end of the joint 

 of each foot, one pair above, the other underneath. The intention 

 of this whole apparatus, and the very long, slender and sharp claws, 

 as well as the elongated and attenuated tarsal joints, is very mani- 

 fest in an animal, destined to roam amid the vertical stalactites, in 

 darkness and in blindness. It is more difficult to comprehend the 

 apparent disproportion of the prothorax, as compared with that 

 part of the body directly behind it. I account for it in this way : 

 it is obvious that it must be difficult for so slow and weak an 

 animal, to procure adequate sustenance in a locality like that 

 which it inhabits ; and that, probably, it is occasionally without the 

 means of procuring food, during a long period. The spacious vault 

 under the elytra seems to indicate, that possibly an accumulation 

 of fat takes place under favourable circumstances, on which the 

 animal subsists in times of scarcity. In the specimens which I 

 examined, the abdomen occupied only a small portion of the 

 vault, and I consider them, therefore, to have been in a lean 

 state. The slowness of motion, and the small respiratory fo- 

 ramina, are in favour of this view ; for we may, I think, consider 

 it as a fact, that the respiration of insects, is in a direct ratio to 

 the intensity of their motion, but in an indirect ratio to the mass 

 of fat. The necessity of a spacious abdomen, and the movements 

 consisting of long steps, determine the necessity of a slender pro- 

 thorax, which can supply the absence of freedom of motion, and 

 afford adequate space for the insertion of legs, fitted to take long 

 strides. 



My first specimen of Stagobius troglodytes, as I call the 

 species, was found seated about ten feet from the ground, on one 

 of the stalactites, in an inner compartment of the Adelsberg cave. 



* Kroyer, 1. c, vol. ii. p. 360. 

 VOL. I. N. S. PART V. JUNE, 1851. I, 



