2. _Nematophycus Storriei_ Barber. Fig. 40. The specimens on which Barber[382] founded this species were obtained by Mr Storrie from the Tymawr quarry near Cardiff, in beds of Wenlock age. The fragmentary nature of the material is largely compensated for by the excellence of the preservation. We may briefly define the species as follows: The stem consists of separate interlacing undivided and usually unbranched tubes of varying diameter. Spaces more or less isodiametric in dimensions are scattered through the tissue. The spaces constitute regions in which the tubular elements branch freely. The main distinguishing features of this British species are (i) the absence of two distinct and well-defined forms of tubular elements. The main part of the stem consists of thick walled tubes similar to those of _N. Logani_, but the spaces between them are occupied by thinner-walled and smaller tubes varying considerably in diameter; (ii) the form of the spaces which are not radially elongated as in _N. Logani_. [Illustration: FIG. 40. _Nematophycus Storriei_ Barb. Longitudinal section, from a photograph by Mr C. A. Barber. × 45.] Fig. 40 shows the undulating course of the tubes as seen in a longitudinal section; the black colour of some of the elements is due to the fact that the surface of the wall is seen, while in the lighter-coloured portions of the tubes the wall has been cut through. The lighter patch about the middle of the figure shows the form of one of the spaces in which the tubes are freely branched. In addition to the two species already described six others have been recorded, but with these we need not concern ourselves in detail. One of these species, _N. Hicksi_, was found by Dr Hicks[383] in the Denbighshire grits quarry of Pen-y-Glog near Corwen in North Wales. The position of these beds has recently been determined by Mr Lake[384] as corresponding to that of the Wenlock limestone. This species and _N. Storriei_ are both Silurian examples of the genus. It is possible, as Barber has suggested, that the specimens described under these two names should be referred to one species. The specimens found by Hicks were small and imperfectly preserved fragments; Etheridge has given a full description of their structure, and Barber has subsequently examined the material. The preservation is not such as will admit of any very precise specific diagnosis; the fragments are correctly referred to _Nematophycus_, but their specific characters cannot be clearly determined.