on the Genus Cermatia, &;c. 305 



The Lepismadcc should be separated most markedly from tlie 

 other division of the T/njsanura with which they are usually asso- 

 ciated ; the antenna^, caudal apparatus, and more especially the 

 mouth, (and the habits of the animals,) having nothing in common. 

 Tlie very name tliat Lamarck has imposed on the order is founded 

 in error. They are not Arachnides antennees trachealcs, and of this 

 you can easily satisfy yourself; detach the scales from the outside 

 with a sable-brush, divide the insect into two halves by a sharp 

 cut from the head to the tail, and under the microscope, by sepa- 

 rating the fleshy interim from the tegument of the bronchi, bril- 

 liant silvery unconnected tubes are seen running upwards and 

 forwards from near the posterior margin of each ring, throwing 

 off numerous branches in all directions, but williout the slightest 

 appearance of trachcce ; the spiracles are excessively minute pores 

 on the lateral parts of the belly, and only to be detected by throw- 

 ing the light through the plates after the scales have been re- 

 moved, and tracing down the bronchi to them. 



As you have remarked, in your observations in the first volume 

 of the Society's Transactions, Mr. MacLeay considered this tribe 

 as the analogues of the Orthoptera, on account of their saltatorial 

 powers ; but I believe it has never been remarked how exceed- 

 ingly closely they are associated with one division of this order, 

 and of these most especially the Achct'idce. For instance, the 

 Orthoptera are distinguished by their want of trachccr ; secondly, 

 compare the caudal appendages, and we find much to strike us of 

 close relationship : then the compound eyes and antenna?, these 

 latter, in both the true Lep'ismcc and Aclietcc, arising by two naked 

 joints supporting long, setaceous, hairy, multiannular terminations ; 

 next the metamorphoses are similar ; and, lastly, the tropin formed 

 on precisely the same model. Turn to your sketches and descrip- 

 tion of Achcla domeslica, at page 440 of your first volume,* and 

 compare them and it with the following description of the man- 

 ducatory apparatus of Lepisma (fig. 4, head and prosternum) : — 

 Labrum somewhat triangular, rounded at the angles. 

 Mandibles solid, with four strong, horny, transverse teeth 



(fig. .5 a, 5 b). 

 Tongue fleshy, filling up the space behind and between the 



mandibles. 

 Maxilla; bilobcd, the outer galeated, partly protecting the inner 



lobe and carrying at its base the .5-jointed palpus. Tlie inner 



shorter and surmounted by two strong incurved tcelh (fig. 6). 



* Introd. to Mod. Class, of Insects. 



