on the Genus Cermaticif Sfc, 303 



intend to capture, and, besides, I am never away from Colombo 

 where insects are by no means plentiful, so t])at I have as yet had 

 little opportunity of making a collection. Of my old pets, the 

 spiders, I bottle up all T see, to be reserved for future examination. 



On turning over Guerin's " Iconographie" some time ago, I was 

 much surprised at his drawing o^ MachyUs iwlypoda ; it resembles 

 mine in no respect, though I see that M. Milne Edwards, in the 

 new edition of Lamarck, unhesitatingly declares both indentical 

 with Lepisma 2^olypoda of Linnc. It shows how necessary 

 sketches are to accompany the descriptions of insects of obscure 

 tribes, and I have no doubt the sketches in question are taken 

 from essentially distinct animals. To be satisfied that they are 

 really distinct, compare the front views of the heads : in mine the 

 labrum (chaperon) is broadly developed, in his elongate ; in mine 

 the maxillary palpi and (in some measure) the labial are robust, 

 in his slender ; similar differences in the antenuce, and, if you 

 might judge from the basal portion of this latter, (figured 1 a, 

 Guerin,) such an extraordinary difference is exhibited that one 

 would hardly imagine they belonged to the same genus ; and still 

 more striking diflferences are discovered in the articulations of the 

 caudal setae. That neither one or other is Lepisma polypoda of 

 Linn^, I have no longer any doubt ; the habitat of this latter every- 

 where given is " Uttorihus Ifqndosis," a locale I never met one in ; 

 all that I have seen have been in dry stone fences, especially when 

 the interstices are overgrown with moss. Fabricius, in his " Species 

 Insectorum," quotes the Linnaean habitat, and moreover adds 

 " aliam simillimam inveni cauda quintuplia," which nearly satisfies 

 me that both are alluding to Leach's Petrobius inarit'tmus, to which 

 the latter observation correctly enough applies, since if a dozen 

 of them be caught such differences occur in the length and 

 appearances of the setae, that on a cursory examination you may 

 hold them as having five setae and be puzzled as to their relative 

 lengths. 



To settle all these difficulties, it only remains for you to request 

 your Swedish correspondents to examine the Lepismidce of their 

 stony shores, assume that Linne drew his description from those 

 found in the habitat he gives, and that they are the true Lepisma; 

 piolypodce, and if they in no ways differ from Leach's insect sink 

 his name and retain MachiUs polypoda for Guerin's, which must 

 clearly be Latreille's, and call mine Mach/Us dispnr. T met with 

 specimens in dry stone fences at Mr. Thompson's seat, three 

 miles from Belfast, which I have a faint recollection of thinking 

 different from that I figured : I wish you would procure some and 



Y 2 



