THYSANOURA. 255 



feet, that experience no metamorphosis, and have, in addi- 

 tion, particular organs of motion either on the sides or the 

 extremity of the abdomen. 



FAMILY I. 



LEPISMENiE, Lat. 



Setiform antennsB divided from their origin into very nu- 

 merous and small joints; mouth furnished with very distinct 

 and salient palpi ; each side of the under part of the abdo- 

 men provided with a range of movable appendages, in the 

 form of false feet ; abdomen terminated by articulated setsB, 

 three of which are the most remarkable ; body always covered 

 with small shining scales. 



It comprises but one genus, the 



Lepisma, Lin. 



The body of these animals is elongated and covered with small 

 scales, frequently silvery and brilliant, from which circumstance the 

 most common species has been compared to a little Fish. The an- 

 tennae are setaceous and usually very long. The mouth is composed 

 of a labrum, of two almost membranous mandibles, of two bipartite 

 jaws, with a palpus consisting- of five or six joints, and of a quadri- 

 emarginated lip bearing two quadri-articulated palpi. The thorax 

 is formed of three pieces; the abdomen, which is somewhat nar- 

 rowed at its posterior extremity, is furnished along each side of the 

 venter with a range of small appendages, supported by a short joint, 

 and terminating in silky points, the last of which are the longest; 

 a sort of scaly compressed stylet, composed of two pieces, issues 

 from the anus; then come the three articulated setae, which are ex- 

 tended beyond the extremity of the body. The feet are short and 

 frequently have very large strongly compressed coxae resembling 

 scales. 



Several species conceal themselves in the cracks in the frame work 

 of windows, under damp boards, in wardrobes, 8cc. Others retire 

 under stones. 



vi; — S. phosphorea, L. — it fell from the clouds on the decks of a vessel one hun- 

 dred miles from the continent. See Zool. Miscell., III. Geophilus maritimus 

 CXL, 1, 2; — G. longicornis, tab. ead., 3 — 6, and some other species. 



