Plagiophrys. 96. Playtiptera polyarthra. 97. Polycoccus. 98. Pollen of pine. 99. Polyhedra tetraetzica. 100. " triangularis. 101. Polyphema. 102. Protococcus. 103. Radiophrys alba. 104. Raphidium duplex. 105. Rotifer ascus. 106. " vulgaris. 107. Silica. 108. Saprolegnia. 109. Scenedesmus acutus. 110. " obliquus. 111. " obtusum. 112. " quadricauda. 113. Sheath of tubelaria. 114.

Testa ovato-subcylindrica, superne laevigata, inferne rugulosa, sordide-rufa; spira obtusa; anfractus 6, secundus tumidus, obliquus, ultimus super aperturam planatus; apertura rotundata; peristoma laete aurantiacum, rimatum, crassum, dorsaliter canaliculatum, infra columellari, profunde sinuatum et in canali contorto excavatum; canalis alter minutus ad partem superiorem et externam aperturae; callus columellaris expansus, appressus.

Here is a new field opened to the adventurous and experimental naturalist: I have trodden it up and down till I am almost weary. To get at it myself I have groped through an alley which may be styled in the words of Ovid: Arduus, obliquus, caligine densus opaca. I pray thee, gentle reader, let me out awhile.

In going up it we found it dark, winding, and intricate beyond any creek that I had ever seen before. When Orpheus came back with his young wife from Styx his path must have been similar to this, for Ovid says it was Arduus, obliquus, caligine densus opaca, and this creek was exactly so. When we had got about two-thirds up it we met the Indians going a-fishing.