1888.] NATURAL SCIENCES OF PHILADELPHIA. 129 



NOTES ON AN AQUATIC INSECT, OR INSECT-LARVA, HAVING 

 JOINTED DORSAL APPENDAGES, 



BY ADELE M. FIELDE. 



I have found liere (at Swatow, China) in May and June, the tem- 

 perature of the air being about 80° F., in still pools of fresh, living 

 water, an insect or insect larva, having upon its back four longitu- 

 dinal rows of jointed ap]:»endages, of nearly the same length as the 

 body of the insect, and capable of being raised, lowered or bent, 

 either by the insect or by external pressure. During this year and 

 last year, I have found over a hundred specimens, varying from i 

 to 8 of an inch in length. Botifera, Vorticella and Oscillatoria with. 

 shreds of vegetable fibre, were attached upon and among the appen- 

 dages. The color varies with the habitat, from pale green to black. 

 As it slowly crawls upon water-plants, it resembles a minute porcu- 

 pine; but it is discerned with difficulty, because of its similarity to 

 its vegetable environment. I have caught my specimens in only 

 one wa}'^ — by taking from the pool, in which I hoped to find them,. 

 a quantity of the water and algse, and keeping these in a basin till 

 the staleness drove the insects to the sides of the vessel, where they 

 escaped the sinking, decaying raft in which they liad been concealed. 

 Several of the larger specimens found have been kept alive for more 

 than a month, in a soup plate in which tlie water was daily changed. 

 They appeared to feed on microscopic objects, probably the heliozoans, 

 rotifers and infusorians, which swarmed on the plate. They neither 

 grew nor moulted within the month, and finally died, oppressed and 

 perhaps suflTocated by the diatoms that stood out like branches from 

 all their appendages, making them look like moss. That these 

 creatures moult in growing is ])roven by the exuviffi of varying size,, 

 found in the waters they naturally inhabit. 



The head is flat, with a pair of large eyes, made up of clusters of 

 six ocelli, projecting from the sides. The antennje are short, six 

 jointed, and just in front of the eyes. The biting mouth-23arts are 

 strong and horny. The three thoracic segments bear three pairs of 

 six-jointed legs, ending in a long claw. All are used deftly in 

 clearing the back from parasites. The second pair is double the 

 length of the first pair, and the third pair a little longer than the 

 second. The abdomen has nine segments, with tlie prominent vent 

 on the ventral side of the posterior segments, which bears two sharp 



