Rev. T. Hincks on the History of the Hydroida. 393 



The locomotive organ perislied, and the zooid in its last stage 

 returned to the condition of the polypite. But in the case of 

 the young Cladonema the umbrella, though everted, continued 

 otherwise unchanged, and manifested its healthy condition by 

 vigorous contractile movements ; it was clear that at any 

 moment it might be restored to its normal position, and 

 discharge its functions as efficiently as ever. 



This peculiarity of habit in the planoblast of the Cladonema 

 no doubt connects itself with the presence of organs of attach- 

 ment, which amongst the natatory gonozooids it alone possesses. 



I may mention that I was unable to detect any thread-cells 

 on the umbrella, nor is there any reference to their existence 

 in Allman's description ; but they are represented in Mr. 

 Holdsworth's excellent figure engraved in my ' History of the 

 British Hydroida'*. 



V. Zanclea {Gemmaria) implexa, Alder. 



I have to record the occurrence of this very beautiful 

 Hydroid at Ilfracombe, where it was found on the Capstone, 

 and dredged up from a moderate depth not very far from shore. 

 In the former locality it grew on Lamtnari'a-roots in the lower 

 rock -pools. All the specimens obtained were spreading over 

 masses of Cellepora, in the orifices of which the polypites were 

 lodged ; Mr. Hodge obtained it in the very same habitat at 

 Seaham Harbour. Hitherto this species has only been met 

 with on the coasts of Northumberland and Scotland. 



The form found in Devonshire is the one first described by 

 Alder as Corytie pelagica, which he subsequently considered to 

 be the young of his Tuhularia ( Coryne) implexa — and is iden- 

 tical with the Coryne hriareus of Allman, and the C. margarica 

 (natural-size figure) of Wright. It is also the one so beautifully 

 figured in Allman's ' Monograph ' as Gemmaria impJexa, the 

 polypites of which are borne on short and simple stems about 

 half a line in height. At first sight this form seems very 

 unlike the Hydroid with branching tubes, growing gregariously 

 and forming "a densely tangled mass" from a half to three 

 quarters of an inch in height, which Alder has described as 

 his Coryne imjplexa. I have little doubt, however, that the 

 two must be referred to the same species. 



I have fine specimens of Zanclea implexa from the Firth of 

 Forth, kindly supplied by Dr. Strethill Wright, in which the 

 two forms are associated. The creeping stolon gives off many 

 short stems enclosed in a polypary, which tapers slightly down- 

 wards and is annulated throughout the greater part of its length, 

 the upper portion, however, being smooth and of more delicate 



* 'History of the British Hydroid Zoophytes/ vol. ii. pi. 11. fig. c'. 

 Ann. & Mag. N. Hist. Ser. 4. Vol. x. 28 



