Mollusks. 



8421 



We push through this tangled thicket towards the river, and hearing 

 a heavy splash are just in time to see a large snapping turtle take the 

 water. The leather-backed and the musk turtle (Trionyx ferox and 

 Sternoth cerus odoratus) are abundant in this river, also many of the 

 more critical forms, but having no books with us we are compelled, 

 rather unwillingly, to ignore their existence. A little further on a 

 narrow creek runs into the river, and here we propose to commence 

 active operations. Where the small stream and river meet is a shady 

 grove. The trees are principally planes (Platanus occidentalis) , often 

 festooned with the graceful winter grape (Vitis cordifolia), sugar 

 maples, red and white oaks, and, rather more rarely, the red mulberry 

 (Morus rubra) and the hackberry (Celtis occidentalis). We pause 

 here and botanize for a short time. The plants of most general 

 interest are Mimulus ringens, Impatiens fulva, Scutellaria lateriflora, 

 Lobelia syphilitica, the Indian plantain (Cacalia suaveolens), the 

 American blue bell (Campanula americana), the bunch berry (Cepha- 

 lanthus occidentalis) and the cup plant (Silphium perfoliatum). At 

 the point where the two streams meet is a small island covered ex- 

 clusively with Dianthera americana. The bottom is gravelly and 

 somewhat pebbly. The shore is strewn with dead valves of Unio, 

 principally U. costatus, indications of the mania for hunting pearls 

 which has existed, and yet does exist, in this village. Having 

 examined many Unionidae, I am led to infer— -fast, that although 

 pearls are most abundant in the animals of the genus Alasmodon, 

 they are not peculiar to that group of shells ; I have found them in 

 the Unio phaseolus, U. gibbosus, U. costatus and U. multiradiatus : 

 secondly, that they may be found in almost any part of the animal 

 except the foot; I have found a tolerably large pearl thoroughly en- 

 veloped in the cardinal muscle of an Alasmodon. 



We proceed to wade into the water, but cautiously, lest we should 

 get our feet badly cut by dead shells. As soon as we are fairly out 

 in the stream, we lift up and examine these defunct mollusks. In 

 them we find Cyclas solidula, Melania depygis, Paludina integra and 

 an Ancylus — alive, also dead shells of Pisidium virginicum and Amni- 

 cola Sayana. The Amnicola Sayana is a terrestrial species, living in 

 damp places with Helix, Succinea and Pupa, and occurs alive near * 

 the banks of the river, about a mile above the spot we are exploring. 

 Occasionally with these we get the American crayfish (Astacus Bar- 

 toni ?) and the curious larva of a Phryganea (?), whose case looks so 

 much like the turbinated shell of a mollusk that Mr. Lea described it 

 as a new species, under the name of Valvata arenifera. The living 



