428 Wisconsin Academy of Sciences, Arts, and Letters. 
upright plants that Hydra luxuriates; Planarians find food on 
the slimy cover of the plants; millions of small Oligochaeta, 
none of them good swimmers^ lope and loop along the plant 
stems; molluscs of all species except the Lamellibranchiataj 
Ancylus, and Pleurocera, make these plants their favorite 
feeding-ground; Hyalella and Hydrachnids are exceedingly 
numerous among the leaves; among may-flies the ubiquitous 
Caenis diminuta is prominent; among caddisworms Leptocella 
uwarowii occurs in prodigious numbers^ and much less fre¬ 
quently Triaenodes flavescens, and the small Hydroptilids; 
among Diptera Chironomus viridis^ C. palliatus^ and Tanypus 
monilis are especially phytophilous, while Tanypus fasciatus 
and Cricotopus exilis will be found less commonly; among 
Coleoptera Haliplid larvae and the adult of Stenelmis mani¬ 
fest a phytophilous tendency. 
B, Recumbent Plants. —These are primarily Chara^ Myrio- 
phyllum, Ceratophyllum, and the various Potomagetons^ ex¬ 
cept amplifolius; they are most abundant between 4 and 6 
meters. Physiologically^ they present a more intricate shelter 
and less exposure to molar activities. Faunistically^ much the 
same biota occur here, but with the difference that Limnaea 
stagnalis may be found more abundant, and that among cad¬ 
disworms Helicopsyche, Molanna, and other bottom forms will 
venture on the trailing leaves of Myriophyllum. Comparably, 
the forms of the upright plants are less abundant, 
G. Barrens.- —Certain deposits of plant marl (i. e. the car¬ 
bonate encrustation of aquatic plants) are frequently found 
among plants; these are frequented primarily by Tanytarsus 
exiguus, Chironomus digitatus, and by adults of Stenelmis crena- 
tus. Practically all other species of the littoral benthos favor 
a sandy bottom. This includes the Lamellibranehiata and 
Pleurocera among molluscs, Helicopsyche and Molanna among 
Trichoptera; Chironomus tentans var ?, C. digitatus, C. lobiferus, 
C. abbreviatus, and Tanytarsus exiguus among Diptera, and 
Stenelmis adults and larvae of Berosus sp. among Coleoptera. 
D. The Rock Reefs. —These reefs occur in various portions of 
the lake, and because of their varying depth are difficult to 
classify. Primarily, they consist of rocks, slabs, and boulders 
of considerable size that may come within 3 meters of-the sur¬ 
face. In practically all places the reefs are without any ad¬ 
mixture of sand or gravel; but their naked surfaces are cov- 
