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head, scarcely tapering, bent obliquely downwards at two-thitds of the 

 way to their tip, and obliquely truncate at tip. On the anterior margin 

 of ventral segments four to ten, in the living insect, is a row of six 

 large, fleshy, roundish, tubercular, retractile pseudopods, the outside 

 ones projecting laterally, and each at tip ti-ansversely striateand armed 

 with short, bristly pubescence ; on the anterior half of ventral joint 

 eleven is a very large, transversely-oval, fleshy, whitish, retractile proleg, 

 with a deeply-impressed, longitudinal stria. On the anterior margin of 

 dorsal joints four to ten, is a pair of smaller, transversely-elongate, re- 

 tractile, fleshy tubercles, covering nearly their entire width, armed like 

 the pseudopods, but not so much elevated as they are. No appearance of 

 any spiracles. Anus terminal, vertically slit, with a slender, retractile 

 thorn .05 inch long, visible in 1860, but not in 1863. Head, and first 

 segment or two, retractile. 



When handled, this larva is very vigorous and restless, and burrows 

 with great strength between the fingers, and even on a smooth table 

 walks as fast as any ordinary caterpillar, either backwards or for- 

 wards ; when placed on its back it progresses with difficulty by the 

 aid of the dorsal tubercles. The external integument is very trans- 

 parent, and as the insect progresses, slides backwards and forwards 

 over its internal organs, like the finger of a glove. When placed in 

 a vessel of simple water it swims vigorously, twice the length of its 

 own body at every stroke, by curving its tail round laterally, some- 

 times to the right, sometimes to the left, so as to touch the side of the 

 fourth or fifth joint, and then suddenly lashing out with it. In such 

 a vessel it keeps all the time close to the surface, and at the end of 

 every stroke, and also when in repose, elevates the anal slit out of 

 the water, on which occasion I once saw a bubble of air attached to it. 

 In the breeding-jar it scarcely ever comes to the surface, but burrows, 

 among the decayed wood, aquatic plants, &c. 



This larva differs remarkably from the one described by DeGeer, 

 in having ventral pseudopods as well as dorsal ones. It might be sup- 

 posed that the dorsal tubercles were branchise, but for the fact that they 

 are found in the earth-inhabiting species described by DeGeer, and that 

 their structure resembles that of the pseudopods. I conjecture that, 

 like the aquatic larva of Prionocyplion discoideus Say (Coleoptera), 

 of whose habits I have given an account in Baron Osten Sacken's 

 Paper on Coleopterous larvae (Trans. Ent, Soc.Philad., I., p.ll7), it has 

 a branchial apparatus issuing from its anus, and that the short, 

 retractile anal thorn, which I saw in 1860, was the form assumed by 

 this apparatus when out of the water. But for a lucky accident, I 

 should have been ignorant of the true form of the expanded anal 

 branchiffi, in Prionocyphon. Occurs from the beginning of June to 



FKOCEEDINGS B. S N, H — VOL. IX. 20 MARCH, 1864, 



