2 68 STIGMARIA. 



for myself his entire series of specimens, and in the Museum at York I saw 

 another highly instructive specimen, which may be briefly noticed in this 

 place. On one side of the block of stone is the mould of the axis of a 

 Stigmaria which has been split nearly through the middle, and in it appear 

 the bases of the appendages in the form of round holes. The cavities 

 corresponding to the appendages run like long tubes through the entire 

 piece of stone, showing the original rounded form. In each of these tubes 

 is a cast of compact, crystalline, milkwhite limestone, which does not how- 

 ever touch the wall, and may therefore be shaken to and fro in its bed. Of 

 course only the basal surface of the cast can be seen filling the orifice of 

 the tubes. On the sides of the block where portions of the stone have 

 been removed, a number of the tubes have been broken off, and the lime- 

 stone cylinders have fallen out. In this case also the space between the 

 imbedding mass and the cylinder is due to the disappearance of the cortical 

 substance which originally lay between them. 



There can be no doubt that the axes of Stigmariae became elongated 

 by apical growth. Unfortunately it is only in comparatively few cases that 

 it has been possible to examine their terminations with precision. They 

 occur according to the statements of authors in two different forms. In 

 the one case the casts become slightly and suddenly smaller towards the 

 top and end in a blunt dome-like termination. An example of this is seen 

 in Goldenberg's l Stigmaria rimosa, in which the scars gradually diminish in 

 size as they approach the apex, and in Stigmaria ficoides 2 , figured in the 

 same place as Stigmaria Anabathra, where the size of the scars remains 

 the same throughout ; von Rohl's 3 specimen, though deformed and less 

 valuable, must also be mentioned here, and a similar dome-like termination 

 has been previously described by Steinhauer 4 . The appendages of course 

 are not preserved in all these specimens. In other cases the extremities of 

 the axes are of very much smaller size ; Williamson has shown me transverse 

 sections of not more than eight millimetres in diameter, which undoubtedly 

 belong to a Stigmaria, and he has figured a preparation of this kind 6 . I have 

 myself found on the refuse-heap of the Gegenort mine at Dudweiler near 

 Saarbrucken a large and still undescribed block, on which I see the ex- 

 tremities of three Stigmaria-axes lying close together in the mould. They 

 diminish rapidly in size and are at last scarcely five millimetres in breadth. 

 Two of them on the outermost margin of the block, the product of a dicho- 

 tomy, appear to be united to one another, but I cannot affirm this with 

 perfect certainty on account of the unfavourable direction of the edge of the 

 fracture. But one of them bifurcates a little below the apex, and the two 

 slightly diverging branches reach a length of about three centimetres, one 



Goldenberg (1), t. la, f. 3. a Goldenberg (1), t. 13, f. 4. 3 von Rohl (1), t. 8, f. 5. 



Steinhauer (1). Williamson (6), t. 9. 



