inO Rov. A. >rATTHinvs' Notes cm Trichopteryiria. 



Tlie labours of Mr. Crotch were latterly coiifiued to the Western 

 side of the Contuient, and more especially to the parts 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. Species such as T. Haldeinanni or 2\ aspera, 

 abundant in the Eastern States, seem to be entirely absent from 

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

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

 Ptcnidiiim and Ptmella, are wholly unrepi-esented in Mr. Crotch's 

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

 ex])ert and successful collectm- of Ptinelhv. With his previous 

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

 would have overlooked situations in which they were likely to 

 occur. Again, genera rarely met with in other parts of the 

 world, appear more abundant in this region. Of the nineteen 

 species which I have examined two belong to the scarce genus 

 Actidiiiiii, and three to Ptiliutii, ,1 form almost exclusiveh" 

 European. 



It must always happen when a collection of Ti-lchopti'viifiid 

 arrives from any fresh locality, that a large numlier of the 

 s]jecios will prove to be distinct from any previously described ; 

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

 most extensive in the whole of the Coleoptera. Nevertheless, 

 Col. Motschulsky met with much immerited vituperation, foi', 

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

 nnd T shall probably be considered guilty of the same crime. 

 I>ut it will 1)6 found impossible to describe or conscientiously 

 distinguish animals belonging to this group on any other plan : 

 individuals, which when examined by an ordinary lens appear 

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

 un<ler a compound power high enough to exhibit their superficial 

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

 C(ir(ihii.<< v)0)iilis bears to its congener C. vei/Kirdli-^. 



Ill distinguishing the species of Tiichojttcrjifiia the sujierficial 

 s(n;l]jture, esjieciallv of the thorax, is a most important diag- 

 nf)stic : so much so that the difference between allied s])ecies 

 may bo more easily recognized by this than any other means, 

 and individuals liTouijed according- to sculi>tuve will generally \»'. 



