British Species of Caddis-flies. 77 
what I have called app. intermed.) placed on each side of the ventral 
margin of the last segment, nearly cylindrical ; between them at 
the base is a triangular plate-like projection. 
Larva with the head small and transverse, corneous. Pronotum 
broader than the head, also transverse and corneous, the superior 
angles not produced. Meso- and meta-nota scarcely corneous, 
of about the same consistency as the abdomen. (See PI. II. figs. 
12, 19.) Abdomen nearly cylindrical. Feet short, hairy. 
Case a cylindrical tube formed of fine sand, somewhat smaller 
at the tail-end, and slightly curved. 
The extraordinary form of the maxillary palpi in the males will 
readily separate that sex, and leave no doubt as to the genus to 
which the insect belongs, but the females are not equally fortunate 
in this respect, and differ widely from the males in the form of the 
palpi. Stephens, in his Illustrations, describes as a separate genus 
Potomaria, Leach, MSS. ; all the types of his three species of this 
genus are females of Sericostoma, yet he describes the male of Poto- 
maria. He also characterizes the anterior tibize as without spurs, 
a statement entirely at variance with the types in his Collection. 
In his characters of Sericostoma he again errs in saying that the 
anterior wings are without transverse neryures, as any one can 
see for himself by simply removing the hairy clothing. 
1. Sericostoma Spencit, Kirby. 
(Pl. IV. fig. 10, neuration; Pl. XI. fig. 19, app.) 
Prosoponia Spencit, Kirb. & Sp. Int. Ent. ed. 2, vol. 3, p. 488 
(1830) ; Sericostoma Spencii, Steph. (*) Ill. p. 184, 1, pl. 33, 
fig. 2; Hag. (*) Ent. Ann. 1859, p. 100, 43; S. Latreillii, 
Curt. (*) Phil.. Mag. p. 214, 1 (1834); SS. collare, Pict. 
Recherch, p. 176, 1, pl. 14, 1 (1834); Brauer (*) Neurop. 
Aust. p. 43, fig. 35, app.; Hag. (*) Stett. Zeit. 1859, 
p- 147, 1; Prosoponia collaris, Kol. Gen, et Spec. Trichop. 
pt. 1, p. 90, 3; Potomaria analis, Steph. (*) Ill. p. 183, 1, 
pl. 34, fig. 4 (1836); P. assimilis, Steph. (*) Ill. p. 183, 2 
(1836); P. hyalina (*) Steph. Ill. p. 183, 3 (1836). 
Antennz brown, not annulated. Palpi in the male blackish, 
fuscous externally, internally with long yellowish hairs. Head 
and prothorax clothed with bright yellow hairs, most evident in 
the female. Meso- and meta- thorax shining black. Legs with 
blackish thighs and testaceous tibize and tarsi, Anterior wings 
uniform golden brown; in the female there are frequently greyish 
blotches at the anal angle and on the opposite costal margin; the 
