OF EXTBA-EUKOPEAN TBIOHOPTEEA. 125 



verse veinlet closing it, is marked in the figure by a dotted line ; but 



I could not clearly determine it). 

 It is an almost invariable rule in Trichoptera that the number 

 of spurs on the posterior tibia? shall equal, or exceed, that of the 

 intermediate. However, in 1863 (Trans. Ent. Soc. Lond. 8rd 

 series, vol. i. p. 492) I described a genus (Anisocentropus) in 

 which the spur-formula was 2, 4, 3, in both sexes, and another 

 {Nesopsyclie) in 1866 Q. c. vol. v. p. 268), with the formula 3,4, 3. 

 And in Ileteroplectron we have a still more remarkable case, the 

 formula being 2, 4, 2 for the S , though regular (2, 4, 4) for 

 the 2 ■ The genus is probably allied to Anisocentropus, somewhat 

 resembling its general form, but differing (besides in the spurs) 

 by the shorter, stouter, and svibserrate antennae, different pro- 

 portions of the joints of the palpi, minor characters of neuration, 

 and the long-fringed posterior tibiae of the <S . But it has little 

 affinity with any other described genus of Leptoceridse. 



Heteroplectron californicum, nov. sp. H. fusco-nigrum. Caput 

 thoraxque aureo-liirsuta. Antennae fuscae. Pedes flavi ; maris tibiae 

 posticse extus fimbriis aureo-griseis longis instructae. Alae anticae 

 fuscae, aureo-pubescentes ; venis venulisque fusco-nigris : posticae 

 fusco-nigraj ( c? $ )• 



Long. Corp. 4|-5| lin. ( = 11-12| mill.); exp. alar. 14-16 lin. (=29- 

 34 mill.). 



Hab. California {in Mus. auct.). 



Blackish fuscous. Head clothed with golden hairs, springing from 

 tubercles on the crown ; thus there is a rounded tubercle on each 

 side close to the eyes, another in front between the basal joints of the 

 antennae (these simulate ocelli), and an elongate one on each side on 

 the posterior margin (when the hairs are removed, these tubercles 

 are seen to be paler brown than the ground-colour) : antennae fuscous 

 or black, somewhat yellowish in some d' individuals, with obsolete 

 darker annulations ; eyes dark coppery ; palpi clothed with fuscous 

 hairs. Prothorax clothed with golden hairs ; and there is a broad 

 line of similarly coloured hairs down the middle of the mesothorax. 

 Legs testaceous, darker in the $ ; in the c? the outer side of the 

 tibiae is fringed with very long greyish-golden, silky hairs, and the 

 tarsal joints have long spine-like tufts of greyish or fuscous hairs. 

 Abdomen blackish ; appendices of the c? somewhat testaceous ; app. 

 sup. elongately triangular, pointed, arising from each side of the 

 middle of the margin of the last dorsal segment, fringed with long 

 golden hairs; app. inf. thick, cylindrical, curved upwards, fuscous 

 at the base, then testaceous, and black at the tips, fringed with long 

 golden hairs; from the interior of the cavity of the last segment 



