370 ENTOMOLOGICAL SOCIETY 



Dr. Gill mentioned the resemblance of certain coleopterous lar 

 vae to certain Trilobites, especially among the Staphylinidae. He 

 said he had been struck by this resemblance in a figure of a Sil- 

 pha larva, even the antennae resembling the antennae of Trilo 

 bites as recently discovered by Beecher. He mentioned the figure 

 of Fluvicola, mistaken for an Isopod crustacean, in De Kay's vol 

 ume on the "Crustacea of New York," and Le Conte's conclu 

 sion that it was the larva of Psephenus, and asked for further 

 information as to this resemblance. 



Mr. Schwarz said that this wonderful resemblance extends 

 through several families of coleopterous larvae. He instanced 

 Micropeplus among the Staphylinidae, various genera of Endo- 

 mychidae, groups of species in the old genus Silpha, Psephenus, 

 and Helichus among the Parnidae, and various genera of the Da- 

 scyllidae and Lampyridae. The resemblance is largely caused 

 by the exfoliation of the sides of the body. What its function is 

 he did not know, some of the larvae possessing it being aquatic, 

 some subaquatic, and some terrestrial 



Dr. Howard jocularly suggested that certain naturalists might 

 consider it to be a case of protective mimicry, since fossil Trilo 

 bites are obviously protected from the attacks of birds. 



The first paper of the evening, by Dr. Dyar, was entitled : 



ON THE FLUCTUATIONS OF THE POST-SPIRACULAR TU 

 BERCLE IN NOCTUID LARY^E. 



By HARRISON G. DYAR. 



At the last meeting of this Society, Prof. J. B. Smith presented 

 a paper giving a classification of the Noctuidae, in which he recog 

 nized a number of tribes based on imaginal characters. While 

 it is true that the larvas of these moths are very uniform and do 

 not present any marked structural differences, I have been attracted 

 by the variations in the position of tubercle iv, or the post-spiracu- 

 lar tubercle, both in different species and on the different segments 

 of the same larva, and I propose to trace out some of the charac 

 ters of the movement of this tubercle in connection with Prof. 

 Smith's classification. 



In the more generalized Lepidopterous larvae, tubercle iv is sit 

 uated well below the spiracle, in line with tubercle v. All the 

 Noctuidae have departed from this condition, and are characterized 

 by having tubercle iv moved up more or less behind the spiracle 



