Stralioiiiyiidae. 15 



flattened. The head is conical: towards the apex, the body tapers 

 more or less, or is rounded. The body consists of twelve segments 

 inciuding the head. The head is more or less cleft above in front, in 

 three somewhat pointed lobes, the median lobe forms a vertical, some- 

 what hooked Jabruni, in front beset with hairs; to each side of it he 

 the mandibles and maxillæ as more or less scale-formed and some- 

 what hooked pieces, strongly beset with bristles and spines or teeth; 

 they are moved together vertically in and out; mandibles and maxillæ 

 are generally more or less connected, so that they may be difficult to 

 discern as separate pieces. On each side of the head there is a more 

 or less distinct eye, and the lateral lobes generally bear antennal 

 papillæ at the point. The larvæ are generally described as peripneustic, 

 and may also be termed so, in as far as there are spiracles on pro- 

 tliorax and (generally) on metathorax and on the flrst six to seven 

 abdominal segments. Such is the case in several genera, but there 

 seems to be some variation in other genera, and especially the meta- 

 thoracic and one or perhaps more of the last abdominal spiracles 

 may be wanting. but the spiracles are often so indistinct, and especially 

 just on metathorax and towards the apex of the abdomen, that it 

 may be very diffieult to decide their actual n amber. The spiracles 

 are in the whole small, tiiose on protliorax being the largest, and they 

 are probably not in function. On the other band there always are 

 terminal spiracles lying in a transverse split on the last segment, and, 

 with the larvæ living in water. surrounded by a coronet of feathery 

 hairs. Thus with regard to tiie function of the tracheal system the 

 larvæ could be termed metapneustic. Tlie pupa is lying in the larval 

 skin, which becomes rigid, but otiierwise does not alter its form. By 

 tiie escape of the imago the larval skin opens with transverse splits 

 on the tliird and fifth segments and a longitudinal split between these 

 in the middle. — All larvæ of Stratiomyids show a peculiar structure 

 of the skin ; it is rather thick, solid and leathery ; seen from the surface 

 it is divided into small, somewhat hexagonal fields, large enough to be 

 seen with a lens, each of these is the base of an inwardly conical 

 calcareous nail, the whole forming a very solid and protective mail; 

 the calcareous matter is present to so high a degree, that the skin 

 bubbles strongly when laid in chloric acid. 



The larvæ live in water, in earlh, dung or in decaying vegetable 

 matter. Some live probably of decaying vegetables, those found in 

 water live, I think, on microorganisms ; when held in captivity they 

 are seen repeatedly to move the mouth parts in and out, and when such 

 larvæ are taken, before they are fuU grown, they generally stop growing, 

 I think for want of suitable food, .when the microorganisms have 

 disappeared. 



