Solms-Laubach[385] has described some fragments of another species of _Nematophycus_ from the Devonian rocks of the Lower Rhine. His specimens are chiefly interesting as extending the geographical range of the genus, and as affording examples of a curious method of preservation. The specimens obtained were small fragments, flattened and very dark brown in colour. The tubular elements consisted of an external membrane of black coal, enclosing a central core of dark red iron-oxide. On burning the fragment on a piece of platinum foil the coal composing the wall of the tubes was removed and the deep-red casts of the tube-cavities remained[386]. The investigation of the structural characters of this imperfect material was conducted by reflected light. Under certain conditions, when it is impossible to obtain thin sections for examination by transmitted light, it is possible to accomplish much, as shown by Solms-Laubach’s work, by means of observation with direct light. The last species to be noticed is _Nematophycus Ortoni_ recently described by Penhallow. There are no concentric rings of growth, no radial spaces and no smaller hyphae in the tissues of this type of stem. In longitudinal section, the tubes show occasional local expansions of the lumen which Penhallow compares with the ‘trumpet-hyphae’ of some recent brown algae. No actual sieve-plates or transverse walls have been detected, but the general appearance of the tubes is considered to afford distinct evidence of the original existence of such walls. The figures accompanying the description do not carry conviction as to the correctness of the reference of the tubes to imperfectly preserved sieve-hyphae. The following list, taken, with a few alterations, from Penhallow’s memoir[387], shows the geographical and geological range of the species of _Nematophycus_ hitherto recorded. ╭ Lower Devonian of Gaspé. _Nematophycus Logani_ (Daws.) ┤ Silurian [Wenlock] of England. ╰ Silurian of New Brunswick. _N. Hicksi_ (Eth.) Silurian. (Wenlock) of N. Wales. _N. crassus_ (Daws.)[388] Middle Devonian of Gaspé and New York. _N. laxus_ (Daws.) Lower Devonian of Gaspé. _N. tenuis_ (Daws.) Lower Devonian of Gaspé. _N. Storriei_ (Barb.) Silurian (Wenlock) of Wales (Cardiff). _N. dechenianus_ (Pied.) Upper Devonian of Germany (Gräfrath). _N. Ortoni_ (Pen.) Upper Erian of Ohio.