174 THE CANADIAN ENTOMOLOGIST 



The genus Pseudachorules, Tullberg, belongs to one of the most generalized 

 of the Collembolan families, the Podurida?. Including the subject of this paper, 

 il ctmiprises as yet only nine species, five of which are reported from Europe 

 and four from North America. Two or three additional species have been 

 described by different authors, only to melt away into the synonymy that is so 

 rife in Collembolan classification. At present the genus is recorded only from 

 the north temperate zone, but they are rare insects, and future collecting will 

 probably discover them in other parts of the world. 



The name "saxatilis" given the species here described, is suggested by the 

 insect's habit of frequenting the rocks where it becomes trapped in the water- 

 worn cups. What attraction a moisture-loving Collembolan can find on the 

 sun-baked wind-swept limestone is hard to understand. Like many other 

 members of its order, this Pseudachorutes seems possessed of a wanderlust- that 

 gets it into trouble. It dees not seem possible that it can live on these bare 

 rocks, and a careful search under stones and in crannies near the rock cups 

 failed to discover a single individual. The fifteen or twenty specimens I have 

 collected were all found caught on the water in the cups. The "mother lode" 

 of this supply has not yet been traced, but it is probably among the bushes and 

 trees a few yards back from the shore. In this respect the name is inaccurate, 

 for the next time the insect is taken it will probably be in dead leaves or under 

 rotten bark. But scientific names are no more to be regarded as strictly de- 

 scriptive than those of persons, and no one expects to find e\ery John Smith 

 hannuering iron on an anvil. 



'c 



Pseudachorutes saxatilis, n. sp. 



Plate V. Figs. 1 to 8. 



Colour light to dark lax'ender blue, finely mottled. Body sutures, legs 

 and under parts lighter. Dividing the width of the back into about thirds, 

 are two rows of small light spots which diverge a little caudally on each seg- 

 ment (Fig. 1). Eye-spots conspicuously black, particularly so in the lighter- 

 coloured specimens. Eyes 8 + 8, equal (Fig. 2). Postantennal organ of about 

 28 oval leaves arranged in a long ellipse (Fig. 3). The number of elements 

 varies from about 25 to 29. Ayilennce sub-equal in length with head or slightK' 

 shorter. Third and fourth segments confluent dorsally, but suture shows 

 ventrally. Relative lengths of segments vary a good deal in difterent individuals, 

 but approximate 7: 8:7:9. First segment about V/iUxwes wide as long, second 

 segment about I'/j times wide as long, third and fourth segments taken to- 

 gether about 2'/2 times long as wide. Fourth segment furnished with "olfactor\'" 

 setie (Fig. 4). Sense-organ of two clavate curving rods situated distal dorsally 

 on third segment (Fig. 5). Antennae bear many single seta^, sparse on lirst 

 and second segments, numerous on third and fourth segments. Buccal cone 

 relatively short. Unguis (Fig. 6) with one large tooth about one-third from 

 base. No tenent hairs, but distal tibio-tarsal hairs are apically bent and minutely 

 knobbed. Fiircula short and stout. Denies with many coarse dorsal tubercles 

 distally. Mucrones (Fig. 7) about one-third as long as denies, convex in out- 

 line, with rounded lamella extending about two-thirds of the length, apical 

 third finger-like, ventral margin curved. Rami of tenaculum tridentale, corpus 



