1845 _Naiadita lanceolata_, Brodie[201]. _Naiadea acuminata_, Buckman[202]. 1850 _Naiadea lanceolata_, Buckman[203]. _Naiadea petiolata_, Buckman[204]. 1900 _Naiadites acuminatus_, Wickes[205]. 1901 _Naiadita lanceolata_, Sollas[206] (figures showing habit of the plant). 1904 _Lycopodites lanceolatus_, Seward[207] (figure showing habit of the plant). [Illustration: FIG. 136. _Lycopodites lanceolatus_ (Brodie). (After Miss Sollas. × 40.) _a_, Sporangium wall; _b_, leaf. _c_, remains of tubular elements in stem.] Specimens referred to this species were originally recorded by Brodie from Rhaetic rocks in the Severn valley, the name _Naiadita_ being chosen as the result of Lindley’s comparison of the small and delicate leaves with those of recent species of the Monocotyledonous family Naiadaceae. The species may be described as follows: Plant slender and moss-like in habit. The axis, which is delicate and thread-like, bears numerous linear acuminate or narrow ovate leaves reaching a length of approximately 5 mm. Under a low magnifying power the thin lamina of the leaves is seen to have a superficial layer of polygonal or rectangular cells arranged in parallel series (fig. 136 _b_). There is no trace of midrib or stomata. The sporangia are more or less spherical and short-stalked, situated at the base of the foliage leaves and containing numerous tetrads of spores. The spores have a diameter of 0·08 mm. Buckman founded additional species on differences in the shape of the leaves but, as Miss Sollas has pointed out, such differences as he noticed may be detected on the same axis. It was stated in an earlier chapter[208] that Starkie Gardner, on insufficient evidence, proposed to place Brodie’s plant among the Mosses. The discovery by Mr Wickes of new material at Pylle hill near Bristol afforded an opportunity for a re-examination of the species: this was successfully undertaken by Miss Sollas who was able to dissolve out spores from the matrix by dilute hydrochloric acid, and to recognise the remains of internal structure in the slender axes by exposing successive surfaces with the aid of a hone. It was found that sporangia occurred at the base of some of the leaves containing numerous tetrads of spores, the individual spores having a diameter of 0·08 mm., apparently twice as large as those of any recent species of _Lycopodium_. Fig. 136 shows a sporangium, _a_, at the base of a leaf, _b_. Indications of tubular elements were recognised in the stem and it is noteworthy that although the outlines of epidermal cells on the leaves are well preserved no stomata were found. The leaves of the recent American species _Lycopodium alopecuroides_ Linn. var. _aquaticum_ Spring[209], which lives under water, possess stomata. It is probable that in _Lycopodites lanceolatus_ the leaves had a very thin lamina and may have been similar in structure to those of recent Mosses; the