IS3B-] 



of the Musquito. 



129 



eulse immediate exit from the shell into the water ; and the concavity 

 of the whole collection, above alluded to, effectually tends to retain the 

 large ends undermost. Had the ova been arranged promiscuously, as 

 to the large and small ends being upwards and downwards, it is evi*= 

 dent that the newly hatched insect, under the former arrangement* 

 would have some difficulty in reaching the water, a difficulty that, most 

 probably, would amount to an impossibility ; one which, at all events^ 

 is effectually prevented by the concave form of the collection. 



A sketch of the newly hatched insect, about 2,500 times the natural 

 size, is given in figure 1. In the chest, or thorax (a), the heart is seen 

 (obscurely however, the body being only semi-transparent), furnished 

 with four projections ; from this organ two blood-vessels proceed down 

 the centre of the body, to the end of the elongation (5), the extreme 

 termination of which is to be seen just above the surface of the water, 

 where the insect lives, for the most part ; the body being suspended^ as 

 it were, from this, head lowermost. 



Between the heart, in the thorax, and the extremity of this singular 

 elongation, an active sanguiferous circulation is to be observed ; in all 

 probability, therefore, it is the seat of the lungs or gills, and it would 

 appear, that a comparatively large supply of air, is essential to the ex-* 

 istence of the insect, as it lives, as much as possible, in this pendulous 

 position at the surface, with the extremity of the elongation rising just 

 above- 



Its motion, which is quick, is effected by a rapid bending of its 

 whole body, so that head and tail (the latter represented at c), and 

 consisting of a bundle of delicate filaments approximate, alternately, 

 on either side of the body it always goes tail foremost, so that the 

 head is dragged along behind. When in search of food, it throws out, 

 in advance of its mouth, a couple of delicate brushes, the individual 

 filaments of which, though seen magnified to the extent above stated, 

 were still of microscopic size. The oval shaped figures in the heacl 

 (d. fig. 1.) represents these brushes when not in use (though obscurely s 

 as the semi-transparent body intervenes). Each of these is put in rapid 

 circular motion, whereby a double kind of whirlpool is occasioned ; 

 whatever food comes within the sphere of these vortices, is speedily 

 devoured. The food appears to be, principally, decomposing vegeta- 

 ble matter, some of which I put into the tumbler, as the vessel in which 

 the ova were discovered contained it ; on this they fed voraciously. 

 They did not, however, entirely confine themselves to a vegetable diet. 

 I was much amused with one, when in a drop of water under the 

 microscope ; in these confined limits its appetite did not forsake it y 

 and the only article of food it found, was the head of one of its own 

 species. So soon as this came within the vortex, it was ravenously- 

 seized, but, being, apparently, too large a morceau, it was let go, after 

 sundry futile attempts at swallowing. It frequently came within the 



