PLATE IV. 



Fig. 151. Navicula Smithii, Breb., p. 197. 



Fig. 152. Navicula Smithii, var. Scutellum, p. 198. 



Fig. 153. Navicula fusca, Greg., p. 198. 



Fig. 154. Navicula littoralis, Donk., p. 200. 



Fig. 155. Navicula oculata, Breb., p. 201. 



Fig. 156. Navicula elliptica, Kiitz and var. ovalis, p. 201. 



Fig. 157. Navicula elliptica, var. oblongella, p. 201. 



Fig. 158. Navicula elliptica, var. minima, p. 201. 



Fig. 159. Navicula praetexta, Ehr., p. 204. 



Fig. 160. Navicula Hennedyi, Wm. Sm., p. 204. 



Fig. 161. Navicula Lyra, Ehr., p. 202. 



Fig. 162. Navicula abrupta, Greg., p. 203. 



Fig. 163. Navicula forcipata, Grev., p. 203. 



Fig. 164. Navicula pygmsea, Kiitz, p. 203. 



Fig. 165. Navicula aspera, Ehr., p. 205. 



Fig. 166. Navicula Tuscula, Ehr., p. 206. 



Fig. 167. Navicula mutica, Kiitz, p. 206. 



Fig. 168. Navicula mutica, var. Goeppertiana, p. 207. 



Fig. 169. Navicula mutica s var undulata, p. 207. 



Fig. 170. Navicula mutica, var. quinquenodis, p. 207. 



Fig. 171. Navicula mutica, var. ventricosa, p. 207. 



Fig. 172. Navicula crucicula, Wm. Sm., p. 207. 



Fig. 173. Navicula crucicula, var. protracta, p. 207. 



Fig. 174. Navicula integra, Wm. Sm., p. 208. 



Fig. 175. Navicula palpebrals, Breb, p. 208. 



Fig. 176. Navicula palpebrals, var. obtusa, p. 208. 



Fig. 177. Navicula palpebralis, var. angulosa, p. 209. 



Fig. 178. Navicula palpebralis, var. minor, p. 209. 



Fig. 179 Navicula palpebralis, var. Barkleyana, p. 209. 



Fig. 180. Navicula brevis, Greg., p. 209. 



Fig. 181. Navicula brevis, var. elliptica, p. 209. 



Fig. 182. Navicula humerosa, Breb., p. 210. 



Fig. 183 Navicula granulata, Breb., p. 211. 



Fig. 184. Navicula marina, Ralfs., p. 212. 



Fig. 185. Navicula Scutum, Schumann? p. 213. 



Fig. 186. Navicula pusilla, Wm. Sm., p. 213. 



Fig. 187. Navicula Schumanniana, Grun., p. 213. 



Fig. 188. Navicula Johnsonii (Wm. Sm.), p. 213. 



Fig. 189. Navicula Johnsonii, var. Belgica, H.V.H., p. 214. 



Fig. 190. Navicula cuspidata, Kiitz, p. 214. 



Fig. 191. Navicula cuspidata, var. halophila, p. 214. 



Fig. 192. Navicula ambigua, Ehr., p. 214. 



Fig. 193. Navicula ambigua, forma craticula, p. 214. 



Fig. 194. Navicula sculpta, Ehr., p. 216. 



Fig. 195. Navicula sphserophora, Kiitz, p. 216. 



Fig. 196. Navicula serians, Breb., p. 217. 



Fig. 197. Navicula serians, var. brachysira, p. 217. 



Fig. 198. Navicula exilis, Grun., p. 217. 



