INVERTEBEATES OF LAKES GENEVA AND MENDOTA. 
475 
9. Gammarus fasciatus Say. Occasional examples occurred. 
10. AUorchestes dentata (Smith) Faxon. This was by far the commonest crustacean, and swarmed 
among the weeds. 
11. Candona elongata ? Herrick. This shelled entomostracan occurred but once in the dredge. 
MOLLUSCA. 
The common mollusks from my dredgings were Unio luteolus and Anodonta footi- 
ana (neither abundant), Planorbis campanulata and other species of that genus, Pisi- 
dium adamsi Pr.,* P. compre.<isum,f 8phcerium solidulum,\ a tew Physas and Limneas 
(tlie former the commoner), an occasional Melantho, a great number of Amnicola cin- 
cinnatiensis, and many examples of Valvata tricarinata and V. sincera. 
VEKMES. 
The worms of these inshore collections were limited to a few leeches and plana- 
rians, occasional specimens of 8tylaria lacustris Linn., and an undetermined species 
of Pristina. 
Besides the foregoing, I obtained here only a small number of water-spiders 
(Hydrachnidse), a few examples of our most abundant darter {Boleosoyna nigrum), and 
a common sunlish {Lepomis). 
DEEP WATER COLLECTIONS, 1881.t 
In the deeper water the collections were not especially different where the bottom 
was covered with vegetation, A haul of the beam-trawl made on a mud bottom in 
the eastern end of the lake at a depth of 12 fathoms, among Ceratophyllum and Ana- 
charts, gave a nearly full assortment of the smaller mollusks of the lake {Valvata tri- 
carinata, V. sincera, Amnicola cincinnatiensis, Planorbis, Physa, Splicerium solidulum, 
Pisidium adamsi, and P. compressum), Physa, Sphccrnim, and Valvata sincera being the 
most abundant. 
Numbers of Chironomus larv®, a dytiscid larva, and a caseworm were the only 
insects, and AUorchestes and Candona the crustaceans of the haul. Among the 
Vermes was a long and slender species (Limnodrilus) with four rows of notched or 
forked setee arranged in short, transverse, comb-like ranks, each of four to six, 
A short haul of the dredge at a depth of 15 fathoms in Williams’ Bay, on a bot- 
tom of sandy mud covered with dead leaves, yielded a single Physa, a small Planor- 
bis, a multitude of Pisidium adamsi, many Valvata striatella, many larvae of Ghirono- 
mus and pupm and pupa cases of Corethra, a few Candona elongata, a multitude of 
dead branches of a polyzoan (apparently Fredrieella), many Limnodrilus, and a few 
examples of Stylaria lacustris. The more highly organized crustaceans and insect 
larvae were here altogether wanting, the principal animals being the smaller mollusks, 
Pisidium and Valvata, the worm-like larvae of gnats, and the slender, reddish worm, 
Limnodrilus, living in the slime. 
A single haul on a mud bottom near the eastern end of the lake, at 19 to 20 
fathoms, gave only large red Chironomus larvae in considerable numbers, several 
* Determined by Mr. H. A. Pilsbry, of the Philadelphia Academy of Sciences. 
t Named by comparison with specimens determined by Mr. G. W. Tryon. 
■ 1 For the opportunity to dredge this lake to advantage I was greatly indebted to Mr. N. K. Fair- 
bank, of Chicago, who placed at my disposal for this purpose his steam-yacht and its crew. 
