ZOOLOGY OF THE BERMUDAS. 135 



5. Mammilli/era tuberculata. Natural size. 



6. One-fourth of a portion of a longitudinal section through 

 the column wall of M. tuberculata. X 200. 



7. Gemmaria Rusei. Natural size. 



8. Transverse section through the gonidial groove of Gem- 

 mar ia Rusei. X 65. 



9. Transverse section through upper part of column of 

 Gemmaria Rusei. X 24. 



HYDROID-CORALS. 



Apparently both of the common West India species of mille- 

 pore, Millepora alcicornis and M. filiformis, are found in the Ber- 

 mudas ; at any rate, forms answering to these are found in our 

 collections. I feel doubtful, however, if the two should not 

 properly be classed as a single species, seeing how great is the 

 individual variation, and how closely the species approximate 

 one another. It is certainly not easy to separate them by the 

 characters which have been generally indicated by systematists. 



