in which small corals are found having attached themselves and then having been overgrown, 



o ooi 



as a series of Bryozoa, attaching themselves to the plant and often overgrown by new layers 

 of accretions, bring about an abnormal thickening of the branches of the plant. If the plant 

 comes into contact with a foreign body, there may even be developed a rather extensive crust, 

 as in several other species in which such a development is not normal. As is the case with 

 L. fruticulosum, L. calcareum and others, it will equally be found with L. australe that 

 germinating plants attach themselves partly to living specimens, partly to dead ones of the 

 same species. If simultaneously or later on Bryozoa or other organisms attach themselves to 

 such specimens, a more irregular development will be the result. In cases of recurrence, coarse 

 forms will come into existence, greatly differing from typical specimens in appearance. Such a 

 peculiar monstrous form of L. calcareum I have described and pictured in Lithoth. Adriat. Meer. 

 Cp. 1. c. pi. 3, fig. i — 7. In the collection in question there are some specimens which are most 

 closely allied to f. ubiana, but coarser than typical specimens of the. form, and approaching 

 very nearly to certain forms of L. fruticulostim. These specimens at all events seem to have 

 partly risen in the said way. Others in which two or more specimens seem to have been melted 

 together, finally assume a shape little typical. If several species are growing gregarious in the 

 same locality, and germs of such ones attach themselves to a different species or to a common 

 substratum, complexes of species will rise like those under L. fritticulosum mentioned; fig. 9. 



As to the structure of this species, it is to be observed that also in this respect the 

 line distinguishing it from other species near of kin is hardly to 

 be drawn with certainty. Indeed it is in part impossible. This is 

 the case in the first place with branched forms of L. fruticu- 

 losum. On the other hand it is all but impossible to draw the 

 line in the said respect between L. australe and L. pulchrum. 

 Besides the forms of L. australe show mutually some variety, 

 as specimens which are quite like each other in habit, are 

 sometimes rather divergent in structure, and even in one and 

 the same specimen the size of the cells is often rather varying. 

 This variation in structure often also corresponds with a varying 

 consistency, which in some specimens is looser than in other 

 ones. A section of L. australe f. amerieaua, parallel with the Fi s- I0 - 



Lithotkamnion australe Fosl. f. amcricana. 



longitudinal axis of a branch, exhibits distinct cup-shaped layers p ar t of amedian section of abranch 5x72. 

 of tissue. The cells of the medullary hypothallium are 14 — 22 a. 



long and 7 — 14 u.. broad, with somewhat rounded corners. The perithallic cells are 8 — 18 u.. 

 long and 7 — 12 u. broad, or here and there roundish and only ó — S u.. in diameter; fiV. 10. 

 A similar section of f. tualensis shows a structure in the main coinciding with that in the latter 

 form. The medullary hypothallic cells are 12 — 22 y.., frequently 14 — 18, seldom up to 25 >j.. 

 long by a breadth of 7 — 12 p.., often with rather rounded corners. The perithallic cells are 

 rectangular, 9 — 18 u.. long by 8 — 10 u.., now and then however roundish; fig. 11. The cells 

 are in general a little shorter, proportionately to the breadth, in this form than in other forms, 

 and the walls of the cells are often thicker. The structure of f. ubiana is rather varying. 



