248 CLAVA LEPTOSTYLA. 



IlahUat. — Growing over the bottoms of exposed rock-pools. 

 Ballnj metrical distribution. — Laminarian zone. 

 Locality. — Shetland Islands, G. J. A. 



This pretty little Clava comes very near to Clava multicornis — so near, indeed, that doubts 

 might at first be entertained as to the justice of regarding it as a distinct species. The scattered 

 condition of its gonophores, however, oflers a character which cannot be set aside. It is true 

 that in at least one other species of Clava, in which the gonophores are habitually clustered 

 immediately behind the proximal tentacles, there may occasionally be met with individuals in which 

 the clusters of gonophores are more or less separated from one another, and carried back for some 

 distance from the tentacles. This is the case in the Clava leptosti/la, Agas., of which a woodcut 

 representing this condition is given by Agassiz,' but I know of no case in which the segregation 

 of the gonophores is carried to such an extent as in the present form, in which the clusters are 

 not only widely separated from one another, but in which many may be seen completely broken 

 up into their component gonophores, which are then scattered singly upon the body of the 

 hydranth. It must also be noticed that this peculiarity was not confined to one or two 

 individuals, but was presented by every gonophore-bearing hydranth of the colony. If to this 

 character we add a greater slenderness of the hydranths and their delicate rose-colour, and 

 further take into consideration the difference in habitat, the hydroid just described being met 

 with at the lowest spring tides, when it is found upon the bottom of shallow rock-pools exposed 

 to the roll of the open sea, we shall find reason to justify us in regarding it as specifically 

 distinct from all other described Clavas. 



It was upon the most exposed shores of the Out Skerries, a small rocky cluster at the 

 extreme east of the Shetland group, that our little clava was obtained. It occurred in shallow 

 rock-pools, overgrown with Lamitiaria. Occasionally some of the hydranths were found with 

 atrophied tentacles, as if showing a tendency to become converted into blastostyles. 



4. Clava leptosttla, Agassi:. 



Clava leptostyla, — Ayassiz, Contr. Nat. Hist. U.S., vol. iv, p. 218, pi. xx, figs. 11 — 16, and 

 pi. xxi. Also fig. 32, on p. 222. Alex. Agassi-, Illustr. 

 Catal., p. 170, fig. 274. Hinclcs, Brit. Hydr. Zooph., p. 6. 



TROPHOSOME. — IlTDKORniZA consisting of a basal expansion formed by closely 

 approximated and coherent tubes, which become distinct only at the extreme 

 margin of the colony. Hydranths much attenuated for some distance from their 

 proximal end, where they spring from the rudimental hydrocaulus, and then, suddenly 

 increasing in thickness, continue cylindrical or slightly tapering to the base of the 

 clavate head ; tentacles from twenty to thirty-five in number. 



^ ' Contr. Nat. Hist. U. S.,' vol. iv, p. 222. 



