2 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 79 



third and fourth antennal joints — in the two latter genera the third 

 joint is longer than the fourth — and by the short epipleura. 



In the country north of Mexico there are few genera besides 

 Galenicella and Monoxia likely to be confused with Trirhabda^ but 

 a few species of two closely related and mainly Central American 

 genera have been found in the United States and described as species 

 of Trirhabda. The species of these genera occurring in the United 

 States are therefore included in this paper. 



The only genus so closely related to Trirhabda as to be doubtfully 

 distinct is the Central American Nesfinus, described by the Rev. 

 H. Clark,2 ^jgQ jj^ 1865. Jacoby^ found little to distinguish the 

 two genera except the larger size of the species of Nestinus. It is 

 evident, however, that in working up the diverse Central American 

 material he referred to Trirhabda species belonging to other genera. 

 The genus Trirhabda as outlined by LeConte is a homogeneous 

 group, and Nestinus does not conform with it either in its larger 

 size and very coarse sculpture or in its nonvittate elytral markings. 

 In all the species of Nestinus thus far described there is no sugges- 

 tion of vitiation, a primary characteristic of Trirhabda. The 

 aedeagus in Nestinus resembles in general shape that of Trirhabda 

 but differs from it in lacking the thinly chitinized groove that in 

 Trirhabda extends medially along the dorsal surface the greater part 

 of its length. 



H. S. Barber, who has long been interested in the problems of 

 nomenclature involved in this group, has kindly prepared the fol- 

 lowing statement designating the genotypes of Trirhabda and a 

 number of related genera : 



Generic concepts of authors not being in agreement and objectionable 

 changes in the application of names being possible, the following list of generic 

 names with genotype designations may be useful; species of Trirhabda have 

 been treated under all except Pyrrhalta, which was wrongly included in 

 Trirhabda by Crotch, 1873 : 



Chrysomela Linnaeus, 1758, 78 species. 



Genotype, Chrysomela popuH Linnaeus, 1758, designated by Latreille, 1810. 



Cryptocephahis Geoffroy, 1762, 12 species without available names except the 

 first and third, under which references to Liunaean species are given. 

 The first species, now Aegialastica alni, was doubtless the best repre- 

 sentative of the genus from the author's standpoint, but the genotype 

 designation by Latreille, 1810, for the Fabrician genus Cryptocephalus 

 can be and is hereby applied to the Geoffroyan genus by tracing back 

 the citations under sericeus by Fabricius and Linnaeus to the species 

 cited by Geoffroy from the prebinomial Fauna Suecica. 

 Genotype, Chrysomela sericea Linnaeus, 1758, designated by Latreille, 

 1810. 



2 Ann. and Mag. Nat. Hist., ser. 3, vol. 16, pp. 324, 325, Oct., 1865. The publishers 

 of the Annals and Magazine of Natural History write, " To our knowledge it has always 

 been published on the first day of the month." 



2 Biol. Centr. Amer. Coleopt., vol. 6, pt. 1, pp. 483, 485, Dec., 1886. 



