105 



lobes seem to be indicated by faintly marked lines on the closed 

 proboscis. The hypostome is also occasionally everted, covering 

 the base of the tentacles (fig. a, Plate II.) 



The whole of the hydranth is, in fact, extremel}^ mutable, 

 bending in all directions, and instantaneously contracting to less 

 than half its full height when touched. When fully extended the 

 tentacles appear as delicate gossamer-hke threads, sparsely studded 

 with large thread-cells, but in the contracted state they become 

 short and thick, with the thread-cells closely packed together. 

 Large oval thread-cells are present also on the body of the 

 hydranth. 



GoNOPHORES. — Borne on the stem on a short stalk ; from one 

 to three in number, in the latter case alternate, with the youngest 

 at the distal end of the stem ; a single medusoid is produced in 

 each. The gonophore is large, cylindrical, with a rounded apex 

 and flattened base, and the gonotheca is thickly studded with large 

 ovoid bodies resembling the thread -cells of the umbreUa (Plate I. a). 

 The young medusoid is of an extremely simple t}^e (Plate Lb), 

 wdth bell-shaped umbrella, short cruciform manubrium, four broad 

 radial canals, four long and four short tentacles springing from 

 pale yellow non-ocellated bulbs. The velum is wide and projects 

 inwards ; there is no sign of any gonads, so that it is impossible to 

 place the medusoid with certainty in any group, but it will probably 

 prove to be one of the Tiarinse (Oceanidje). Further research on 

 this point is necessary, however. 



Gonophores produced from February- June. 



Locality and Habitat. — From 40 miles N.E. of Shields, in 

 45 fathoms, growing on an old shell of Volsella modiolus : and on 

 stones in the Laboratory tanks, where large colonies were observed 

 setting free medusoids. 



Since writing the above I have received from Dr. E. Stechow, 

 of the Zoological Museum, Munich, his interesting paper " Ein 

 thecenloser Hydroid, der mit einer Leptomeduse in Generations- 

 wechsel steht " (reprinted from the " Zoologischer Anzeiger," Bd. 

 XLL, Nr. 13, April, 1913), describing the gymnoblastic Hydroid 

 Campanopsis duhia reared from the Leptomedusa " Octorchis " 

 (Eutima campanulata, Glaus, 1876). 



