266 rBESH-WATEE AQUAEIA. 



curious fan (j) composed of delicately-plumed bristles attached 

 to the under-part of the last segment of the body. With the 

 help of this fan the larva forces and steers its way through 

 the water. It is also connected, so it is supposed, with the 

 tracheal system. Posterior to this organ there are two curious 

 and much-curved hooks (k), the use of which I do not know. 

 Dr. Carrington, in his very interesting article upon this 

 larva in Science Gossip, for April, 1868, suggests that they 

 are utilised during the creature's transformation. Several of 

 these larvae have become pupse, and the pupse have changed 

 into perfect Midges, while in my possession ; but I have never 

 noticed the hooks made use of in any way. I represents four 

 bronchial leaflets, and above them there are four more plumed 

 bristles (m). Upon different parts of the body of the creature 

 there are very curious hairs, which are simple at their root, 

 but afterwards become compound. Sometimes as many as 

 seven or eight branches spring from a single stem. The 

 organs of respiration of this larva are very difficult to trace, 

 owing to their minuteness ; but the appendages at the extremity 

 of the creature's body are so formed and so connected with 

 the tracheal system that the animal, unlike most of the larvse 

 of the Diptera, seems to have no need of coming to the sur- 

 face of the water for air. 



I have given rather a long description of this larva, because 

 of the unusually curious and interesting formation of its body, 

 and I am sure that if anyone who does not know the animal 

 will examine it carefully, he will be amply rewarded for his 

 pains. A little trouble will certainly be required, for 

 though the creature is so strangely transparent, it is by no 

 means easy to investigate closely, owing to its restlessness. 

 Frequently when one sees it conveniently near to the side of 

 the vessel in which it is confined, and just as the magnifying- 

 glass has been placed in position, the creature, with a power- 

 ful stroke of the extremity of its body, will shoot out of focus. 

 A good plan, to simplify the examination, is to put two or 

 three of the larvae in a very clear glass bottle, of not more 

 than lin. and not less than fin. in diameter. One animal at 

 least will be almost certain to be in the right position for the 



