large intermixed, 'i^ofmii has yet been observed. A longitudinal section 

 of a phyllodium shows a broad and very dense and compact medullary stra- 

 tum, formed of very minute and slender cylindrical cellules, placed longi- 

 tudinally, and in a filiform series, but scarcely connected with definite fila» 

 ments; and a narrower cortical layer of many rows of roundish, coloured 

 cells. The colour is a dark brown-red, passing through dull-orange into 

 dirty-white or greenish. The substance is extremely hard and rigid, and 

 shows no tendency to adhere to paper in drying. 



Our figure represents but a small portion of a proliferously 

 much branched frond, which would more than cover a quarto 

 plate, and which is also more thickly beset with leaf-like branches 

 {phyllodid) than the figure exhibits. While the structure and 

 rigid substance are very similar in this to what they are in T. 

 JlahelUforme, given in our last Plate, the habit is different. 

 Instead of the coating of interlaced fibrils which constitute so 

 large a part of the " phi/UocUa " in T. flabelliforme, we have 

 here minute echinated papillae, which are never developed into 

 filaments, and merely serve to roughen the surface. Similar 

 papillae are found in other species, with which the present 

 nearly agrees in habit and structure. 



This is the largest and finest species of Thamnoclonium, and 

 is inscribed to the memory of the late Dr. Charles Lemann, 

 F.L.S., of London, a distinguished botanist and estimable man, 

 to whom I am indebted for the first specimen received. It was 

 included in a parcel of Algae collected by Mr. Mylne, in Western 

 Australia, and sent to me by Dr. Lemann. It seems to be of 

 very rare occurrence, and has not as yet been sent by Mr. 

 Clifton, in whose neighbourhood it is found. 



Fig. 1. Thamnoclonium Lemannianum, — the natural size. 2. Small portion 

 of the surface, showing the spinous tubercles. 3. Section through the 

 frond. 4. Small portion of the same, to show the different cellular struc- 

 ture in the medullary and cortical layers : — the latter figures variously mag^ 

 nified. 



