Vorhies—Studies on the Trichoptera of Wisconsin. 693 
possibly be confounded, however, as dilutus is very light with a 
few slightly darker markings, while ancylus is nearly black on 
the head and prothorax with the markings in white. 
Pupa. —Length, 7-8 mm. Width, 1.5 mm. Antennae coiled 
about the posterior end of the abdomen. Body in life light 
green. Dorsal spines, III, 2. 3. 3-4 + 15-18. 3. 2, VII. 
First abdominal tergum with lateral borders of chitin, ending 
posteriorly in knobs studded with short blunt spines: within 
these knobs, on the posterior edge of the segment, a pair of 
spiny patches, a little more conspicuous than in dilutus. Lat¬ 
eral line inconspicuous, beginning on the 3rd segment and ex¬ 
tending over the 8th. The gills are branched, each with 2-5 
branches, but are quite small and their position difficult to deter¬ 
mine exactly. The formula appears to be as in Fig. 11. 
It will be noticed that this pupa is almost identical with the 
one preceding, but peculiarly, the case is here an unfailing spe¬ 
cific character, so far as these two species is concerned. One 
can also make certain of the identity of a pupa if a fairly ma¬ 
ture male specimen is at hand. After preserving such an in¬ 
dividual, the genitalia may be seen thru the skin, or, better yet, 
the posterior end of the pupal skin may be dissected away and 
the organs be thus clearly exposed. 
Case. —Length, 7-9 mm. Width, anterior, 4-5 mm.; pos¬ 
terior, 1 mm. This case, remarkable for a Leptocerus, has the 
form of a Molanna case or, better, that of a Tliremma, i. e., the 
tube proper is concealed by a dorsal shield formed by anterior 
and lateral extensions, giving it the appearance of a shell of 
the snail Ancylus. The larva is well protected and clings 
closely to the rocks on which it is found, usually on the lower 
surface. The structure is of fine sand grains, neatly fitted. 
The round opening of the posterior end is situated on a small 
projection of silk on the dorsal side. 
At the time of pupation, the space beneath the anterior end is 
floored with silk, and a small transverse slit is made in the an¬ 
terior end on the dorsal side. The upturned appendages of the 
posterior end* of the pupa may usually be seen projecting out 
of the posterior opening as in dilutus. Though this case ap¬ 
pears at first so remarkably different from that of the preceding; 
