80 [Sepembcr, 



side of the surface of the water, exactly like a fly on the uudtr-side 

 of a pane of glass ; a thin film of air contained between the abdomen 

 and the projecting sides of the elytra seemed to serve as a kud of 

 float, and support them. 



On May 19th, I was very pleased to see that one of the specimens 

 had developed an egg-bag : the bag is formed of a tough ■whitish 

 membrane, and covers the whole of the abdomen : at fii'st it was con- 

 tained within the projecting sides of the elytra, but by May 25th, it 

 had swollen beyond them : on May 28th, it was very much swollen, 

 and the shape of the eggs (a long oval) was quite visible ; unfortu- 

 nately, I did not look at the beetle again for two or three days, as I 

 was much occupied, and, therefore, missed the hatching period, but on 

 May 81st, I found that the egg-bag had disappeared, and that a num- 

 ber of larvje (about 100) were hatched out. I at once noted that, al- 

 though so entirely different in shape, they walked on the under-side of 

 the surface of the water back downwards, exactly like their pai'ents : 

 occasionally, they would crawl below upon the plants, but did not stay 

 for long, and immediately on letting go their hold of the plant, they rose 

 rapidly to the surface : apparently, it is impossible either for the larvae or 

 perfect insects to go beneath the surface of the water unless they can 

 manage to cling to some plant and crawl down ; on examination of 

 some specimens of the larvse mounted in glycerine jelly, I found the 

 tracheae very largely developed, and the quantity of air thus contained 

 within the body would explain the fact ; the trachea? end at the tail, 

 through which the insect apparently mainly breathes : it never, how- 

 ever, assumes a perpendicular position like the larva of the gnat, but 

 always keeps a horizontal one, with all its legs at the surface, and 

 its tail curved upwards to meet the air. 



I hoped to follow the insects through further stages, and divided 

 them into three lots, but, by June 5th, all the first lot had died, and, 

 by June 9th, the second lot, all but one or two, had died also ; on 

 June 10th, I found out the reason, for I caught them in the act of 

 devouring one another, an operation for which their huge jaws pecu- 

 liarly fitted them. I then separated the very few remaining out of 

 the three lots, but it was of no use, as the last died on June 12th. 

 The original beetles are now (Aug. 9th) well and thriving, and will, 

 I hope, continue so, as Mr. Billups tells me that a railroad is likely to 

 be run through the locality they came from, and that Spercluus is 

 likely again to become in time one of our greatest rarities. 



The lai'va is so peculiar, especially as regards its mouth joarts, that 

 I got Mr, Matthews to dissect it, which he has done with his usual 



