348 Mr. J. R;ilfs on the Mode of Growth in Calothrix, cVc. 



Fiff. 3. The branched chambers of Ciiona celata exposed by the removal of 

 the sTirface of the matrix : a, papillary punctui'es. 



— 4. Spicula of C. celata miicli enlarged. 



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



times. 



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



tures : — natural size. 



— 7. Spicula of C. spinosa much enlarged. 



— 8. Triradiate spicula from tlie surface of Thoosa bulbosal 



Platc XIV. 



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

 of the matrix, a little enlarged : a, 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, d, e, f, the succeeding 

 stages. 



— 5. Spicula of C. Northumhrica much enlarged. 



— 6. Ditto C. gorgonioides ditto. 



— 7. Ditto C. gracilis ditto. 



— S. Ditto C. Howsei ditto. 



— 9. Ditto C. Fryeri ditto. 



— 10. Ditto C. Canadensis ditto. 



Plate XV. 



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

 of the matrix : a, papillary punctures. 



— 2. Spicula of C. coralUnoides umch enlarged. 



— 3. Ditto C. radiala ditto. 



— 4. Ditto C. dendritica ditto. 



— 5. Ditto C. insidiosa ditto. 



— 6. Ditto C. quadrata ditto. 



— 7. Ditto C. labyrintkica ditto. 



— 8. Ditto C. cervina ditto. 



— 9. Ditto C. Alderi ditto. 



— 10. Ditto C nodosa ditto. 



— 11. Ditto C. muscoides ditto. 



— 12. Ditto C. vastifica ditto. 



— 13. Ditto C. angulala ditto. 



XXXVII. — On the Mode of Grorvth 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 Calothriw and other genera are 

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

 in OsciUntoria and Microcoleus. 



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



