624: NEUROPTERA. 



PoDURiD^ Biirmeister. The Spring-tails are the t^'pical 

 Thysanura, as the}' differ more than Lepisnia and allies from 

 all other insects. The anal bristles, which are free in Lepisma. 

 are here united and bent beneath the body, forming tlie 

 ■•spring" by which the}' leap to a prodigious height for such 

 minute insects. The body is cylindrical, not flattened, and is 

 covered either Avith hairs or scales. The four or six-jointed 

 untenuiB are short and thick, and the e3'es are simple, usually 

 four to eight on each side. The mouth-parts are not well de- 

 veloped, thougli mostly present, the mandibles being small, 

 with minute teeth, antl the maxillary palpi entirely wanting 

 (CJerstaecker), tliough Lubbock states that the "second pair 

 of maxilUe [labium] are membranous and delicate." The pro- 

 thorax is small, convex, while the two hinder thoracic rings 

 are large and similar to each other. Tlie legs are stout, with 

 tarsi consisting of but a single joint. The abdomen consists 

 <»r six, sometimes only three segments, with a long anal stylet 

 Ibrming the forked tail, or "spring," beneath. (Gerstaecker.) 

 They are found in gardens, or hot-beds, on maiuire heaps iu 

 Avinter, and on the snow ; they may also be seen leaping on the 

 surface of the water in quiet pools. According to Nicolet 

 these insects are very prolific, as he found 1360 eggs in a sin- 

 gle individual. The embryo is developed in twelve days. 

 They moult often, and at periods of fourteen days each. 



The intestinal canal consists in great part of a long and 

 voluminous chyle-making stomach, into the lower end of which 

 six free Malpighian tubes pour their contents. (Nicolet.) In 

 Pajnrius Saundersii, as in man}' other aptei'ous Articulata. the 

 testis is formed on the same type as the ovary. On each side 

 of the body is a simple tube opening into a triangular reser- 

 voir with its base in front. The nervous system of Smynthurns 

 consists, according to Nicolet, of four ganglia, with a double 

 connecting cord. Two of these ganglia occupy the head and 

 Ibrm the oesophageal collar. The two others consist of a tho- 

 racic and one abdominal ganglion. There are in Podura four 

 pairs of stigmata in the four basal rings of the abdomen. Next 

 to the two main trachea* are six pairs of rather long vesicles 

 united with them by loops. (Gerstaecker.) 



Lubbock states that in Smynthurns there are but two spira- 



