84 Mr. H. T. Stalnton ow Entomological Difficulties 



XT 1 1. On some of the Difficulties of Entomological Stu- 

 dents, as exemplified by recent Experience in the Genus 

 Elachista. By H. T. Stainton, Esq. 



[Read 2nd October, 1854.] 



A VERY useful paper by M. Godet appeared in tlie first volume 

 of the " Annales de la Societe Entomologique de France," p. 34, 

 entitled " Quelques Observations sur la Maniere de travailler en 

 Histoire Naturelle, et en particulier sur les Monographies." The 

 object of this was, as its title implies, to point out the best way to 

 proceed in working out groups monographically ; and this paper 

 may be read with real advantage by students at the present day, 

 and none can read it without pleasure. 



M. Godet says at page 39, " Pour faire une bonne Monogra- 

 phie, il faut avoir une connaissance exacte de I'anatomie du groupe 

 d'insectes dont on s'occupe, faire I'histoire de leurs transformations, 

 de leurs moeurs, de leurs habitudes, des substances vegetales ou 

 animales dont ils aiment a se nourrir. 11 faut lire les ouvrages de 

 tous les auteurs qui se sont occupes du groupe qui fait I'ohjet des 

 travaux du monographe. A cette partie se rattache la synonymie, 



si souvent negligee et si eminemment necessaire Ce 



n'est qu'apres s'ctre enrichi d'une masse d'observations faites par 

 d'autres ou par lui-merae que le monographe doit proceder seri- 

 eusement a la fixation definitive des especes, a 1 enonce de leurs 

 caracteres, a leur description et a I'etablissement des groupes 

 artificiels ou naturels." 



How true all this is, all who have worked monographically must 

 have felt, and must have found it no light task they had under- 

 taken. 



To chronicle observations made, to describe specimens placed 

 before one, is one thing ; but to define the limits of the variations 

 of species, to make the observations necessary to supply some 

 gap that is perceptible, are very different matters, and the mono- 

 grapher has this to do, or he fails of his intended end. Passing 

 over the " connaissance exacte de I'anatomie du groupe," I wish to 

 offer a few remarks on the second point, " faire I'histoire de leurs 

 transformations." To do this, it is necessary to know, 1°. Where 

 the egg is laid ; 2°. How soon it is hatched ; 3". How long the 

 larva lives before changing its skin ; 4°. What change (if any) in 

 the form and markings of the larva takes place when it changes 

 its skin; 5". At what period the larva will be full fed; 6". What 



