liU] Roy. A. Mattiikws' i\V//^'.<! o?? Trichopterygia. • 



The laboTivs of Mr. Crotcli were lattei'ly confined to the Western 

 side of the Continent, and more especially to the jiarts bordering 

 on the Pacific Coast, on this account the species which he met 

 with differ much from those which inhabit the Eastern or 

 Atlantic States. Sj^ecies such as T. Haldemanni or T. aspera, 

 abiindant in the Eastern States, seem to be entirely absent frona 

 those on the other vside, where their places are supplied by forms 

 of a different and more European type. Some genera, as 

 Pteniiliinn and FthifUa, are wholly unrepresented in Mr. Crotch's 

 collections : this is the more surprising as Mr. Crotch was a most 

 exjjert and successful collector of PtinelUi'. With his previous 

 knowledge, therefore, of their habits it is not probable that he 

 would have overlooked situations in which they were likelv to 

 occur. Again, genera ra,rely met with in other ])arts of the 

 world, a])pear more abundant in this region. Of the nineteen 

 s])ecies Avhich I have examined tAvo belong to the scai'ce genus 

 Arti(lhi/ii, and three to J^tilimii. a form almost exclusiveh' 

 European. 



It must always happen when a collection of I'l-ifliopti'viifiia 

 arrives from any fresh localitv, that a large number of tlie 

 species will prove to be distinct from any previously described ; 

 indeed, I believe the genus Trichojiteryx alone to be one of the 

 most extensive in the whole of the Coleojitera. Nevertheless, 

 VaA. Motscluilsky met with much unmerited vituperation, for, 

 as his critics are pleased to term it, making so many new species, 

 and I shall probably be considered guilty of the same crime. 

 But it Avill 1)6 found im])ossilde to describe or conscientiously 

 distinguish animals l)elonging to this groiip on any other plan ; 

 individuals, which Avhen examined by an ordinary lens appear 

 sufficiently similar to belong to the same species, will, if placed 

 under a compound power high enough to exhibit their superficial 

 sculpture, be found to bear the same affinity to each other as 

 Gurahis monilis bears to its congener C. nemoraJift. 



In distinguishing the species of Trlchoptenigia the sui^erficial 

 sculpture, es]~)eciallv of the thorax, is a most im])ortant diag- 

 nostic : so much so that the difference l^etween allied species 

 mav be more easily recognized liy this than any othoi- means, 

 and individuals grou])ed according to scul])ture will gonerrdl}- be 



