We may pass over various notes and additional contributions by Dawson, who did not admit the corrections to his original descriptions which Carruthers’ work supplied. In 1889 an important memoir appeared by Penhallow[372] of Montreal in which he confirmed Carruthers’ decision as to the algal nature of _Prototaxites_; he contributed some new facts to the previous account by Carruthers, and expressed himself in favour of regarding the fossil plant as a near ally of the recent Laminariae. The next addition to our botanical knowledge of this genus was made by Barber[373] who described a new specific type of _Nematophycus_—_N. Storriei_—found by Storrie in beds of Wenlock limestone age near Cardiff. Solms-Laubach[374], in a recent memoir on Devonian plants, recorded the occurrence of another species of this genus in Middle Devonian rocks near Gräfrath on the Lower Rhine. Lastly Penhallow[375], in describing a new species, lays stress on the resemblance of some of the tubular elements in the stem to the sieve-hyphae of the recent seaweeds _Macrocystis_ and _Laminaria_. He concludes that the new facts he records make it clear that _Nematophycus_ “is an alga, and of an alliance with the Laminarias.” The recent evidence brought forward by Penhallow is not entirely satisfactory; the drawings and descriptions of the supposed trumpet-shaped sieve-hyphae are not conclusive. On the whole it is probably the better course to speak of _Nematophycus_ as a possible ally of the brown algae rather than as an extinct type of the Siphoneae, but until our knowledge is more complete it is practically impossible to decide the exact position of this Siluro-Devonian genus. Solms-Laubach[376] has suggested that the generic name _Nematophyton_, used by Penhallow in preference to Carruthers’ term _Nematophycus_, is the more suitable as being a neutral designation and not one which assumes a definite botanical position. In view of the nature of the evidence in favour of the algal affinities of the fossil, the reasons for discarding Carruthers’ original name are hardly sufficient. Before discussing more fully the distribution and botanical position of _Nematophycus_ we may describe at length one of the best known species, and give a short account of some other forms. • • • • •