316 Proceedings of the Boy al Physical Society. 



has lately met with the present species in the Firth of Forth, 

 has ascertained that it produces planuloid young direct from 

 the summit of the ovarian sac. This affords another proof 

 of the difficulty of establishing a genus from the mode of 

 development. 



I have met with this species occasionally, for some years 

 past, on stones and the roots of Laminarice at Cullercoats 

 and Tynemouth. From its minute size, it requires to be 

 carefully looked for. 



Explanation of Plate XIV. 



Fig. 1. Polypary of Hydractinia areolata on Natica Alderi, natural size. 



Fig. 2. Hydractinia areolata, highly magnified. 



Fig. 3. A portion of the polypary of the same, highly magnified. 



Fig. 4. Medusoid of the same, highly magnified. 



Fig. 5. Atractylis arenosa, natural size. 



Fig. 6. The same, highly magnified. 



Fig. 7. A tentacle of the same, much enlarged. 



III. On Reproduction in ^Equoria vitrina. By T. Steethill 

 Weight, M.D. Plate XV. 



In vol. i. of Agassiz's " Natural History of the United 

 States/' the following passage occurs : — " As to the iEquo- 

 riadee, I have no doubt that they are genuine hydroids, 

 though I have not been able to trace with certainty the 

 origin of the iEquoria of our coast to any true hydroid. 

 But the structure of iEquoria in its adult Medusa state is 

 so strictly homologous to that of all the naked-eyed Medusae, 

 that even if it were ascertained that it undergoes a direct 

 metamorphosis from the egg to the perfect Medusa, I would 

 not hesitate to consider it as a member of the order of 

 Hydroids, since it has simple radiating aquiferous tubes, a 

 circular canal, and marginal tentacles closely connected with 

 it, and provided with minute pigment spots at the base." 

 Agassiz was doubtless correct, and he might also have pre- 

 dicted that it belonged to the genus Campanularia or Lao- 

 medea, as it corresponded with those genera in the presence 

 of otoliths. In the beginning of this month (November) 

 Mr Fulton sent me two living specimens of JEquoria vitrina, 

 one about three inches in diameter, the other about six 



