348 Mr. J. Ralfs on the Mode of Gj-owth in Calothrix, ^r. 



Fig. 3. The branched chambers of Cliona celata exposed by the removal of 

 the surface of the matrix : a, papillary punctures. 



— 4. Spicula of C. celata much enlarged. 



— 5. C. spinosa as seen through the transparent matrix, magnified two 



times. 



— 6. A portion of the surface of the matrix exhibiting the papillary punc- 



tures : — natural size. 



— 7. Spicula of C. spinosa much enlarged. 



— 8. Triradiate spicula from the surface of Thoosa hulbosa t 



Plate XIV. 



Fig. 1 . Chambers of C. gorgonioides exposed by the removal of the surface 

 of the matrix, a little enlarged : o, papillary punctures. 



— 2. C, Fryeri as seen through the transparent matrix; one half en- 



larged. 



— 3. Surface of the matrix of the same, exhibiting the papillary punctures. 



— 4. A series exhibiting the development of C. Fryeri considerably en- 



larged : a, represents the first stage ; h, c, c/, e, f, the succeeding 

 stages. 



— 5. Spicula of C. Northumhrica much enlarged. 



— 6. Ditto C. gorgonioides ditto. 



— 7. Ditto C. gracilis ditto. 



— 8. Ditto C. Howsei ditto. 



— 9. Ditto C. Fryeri ditto. 



— 10. Ditto C. Canadensis ditto. 



Plate XV. 



Fig. 1 . Chambers of C. corallinoides exposed by the removal of the surface 

 of the matrix : a, papillary punctures. 



— 2. Spicula of C. corallinoides much enlarged. 



— 3. Ditto C. radiata ditto. 



— 4. Ditto C. dendritica ditto. 



— 5. Ditto C insidiosa ditto. 



— 6. Ditto C. quadrata ditto. 



— 7. Ditto C, labyrinihica ditto. 



— 8. Ditto C. cervina ditto. 



— 9. Ditto C. Jlderi ditto. 



— 10. Ditto C. nodosa ditto. 



— 11. Ditto C. mnscoides ditto. 



— 12. Ditto C. vastifica ditto. 



— 13. Ditto C. angulata ditto. 



XXXVII. — On the Mode of Growth in Calothrix and allied 

 Genera. By John Ralfs, M.R.C.S., Penzance*. 



In my former communication I remarked that in Oscillatoria the 

 division of the filament is accompanied by that of its sheath, 

 whilst in Microcoleus the sheath is so inflated as not to interfere 

 with the process of division. I shall now endeavour to prove 

 that the appositional branches in Calothrix and other genera are 

 the results of modifications of that mode of division which we see 

 in Oscillatoria and Microcoleus. 



* Read before the Botanical Society of Edinburgh, 8th March, 1849. 



