The drawings have all been made with an Abbé camera lucida, a 3 mm. objective and a No. 10 eye-piece, producing a magnification of about 800 diameters. All illustrations are from actual specimens in my cabinet or, in a few instances, from slides sent me by friends. In the measurement of striæ and puncta, the number in ten microns is stated, and will be found to be approximately correct in most of the drawings, except when the number is in excess of twenty in ten microns, in which case it is impossible to represent the markings accurately on figures of the magnification adopted. All drawings are from specimens in this locality, except in a few cases mentioned in the text.
PAGE Achnanthes, 58 brevipes Ag., 59 coarctata (Bréb.) Grun., 59 danica (Floegel) Grun., 60 exigua Grun., 59 inflata (Kuetz.) Grun., 59 lanceolata (Bréb.) Grun., 59 linearis forma curta H.L.S., 59 longipes Ag., 58 subsessilis Kuetz., 59
Actinocyclus, 26 barkleyi var. aggregata Rattr., 27 ellipticus var. delawarensis n. var., 27 moniliformis Ralfs, 27
Actinoptychus, 24 _cellulosa_ Ehr., 24 heliopelta Grun. var.?, 25 _omphalopelta_ Ehr., 24 undulatus (Kuetz.) Ralfs, 24 vulgaris var. interrupta n. var., 24
Amphipleura, 78 pellucida Kuetz., 78 rutilans (Trentepohl) Cl., 78
Amphiprora, 68 alata Kuetz., 68 conspicua Grev., 68 _lepidoptera_ Greg., 69 ornata Bail., 68 paludosa Wm. Sm., 68 pulchra Bail., 68
_Amphitetras_, _antediluviana_ Ehr., 32 _tessellata_ Shad., 32
Amphora, 65 acuta Greg., 66 angusta var. eulensteinii Grun., 67 _aponina_ Kuetz., 66 arenaria Donk., 67 areolata Grun., 66 coffæiformis (Ag.) Kuetz., 66 crassa Greg., 65 _eulensteinii_ A.S., 67 gigantea var. fusca A.S., 65 _insecta_ Grun., 69 lævis Greg., 66 lineolata Ehr., 66 _mucronata_ H.L.S., 69 obtusa Greg., 67 ocellata var. cingulata Cl., 67 ostrearia Bréb., 66 ovalis (Bréb.) Kuetz., 65 var. libyca (Ehr.) Cl., 65 var. pediculus (Kuetz.) Cl., 65 _plicata_ Greg., 66 _porcellus_ Kitton, 66 proteus Greg., 65 _quadrata_ Bréb., 66 robusta Greg., 65 _salina_ Wm. Sm., 66 _vitræa_ Cl., 66
Anomoeoneis, 80 follis (Ehr.) Cl., 80 serians Bréb., 80 sphærophora (Kuetz.) Cl., 80
Anorthoneis, 56 excentrica (Donk.) Grun., 56
Asterionella, 50 formosa Hass., 50 inflata Heib., 50