372 YORTICLAYA HUMILIS. 



Mr. Hincks's specimens, oLtained during the summer in the north of Devonshire, were furnished 

 with them.^ 



Wrio-ht and Hincks describe the fihform tentacles which compose the proximal verticil as 

 directed away from the hydrorhiza. In my specimens they always pointed towards the 

 hydrorhiza — a difference, however, which may not be constant, and cannot in itself be regarded as 

 specific. 



VOETICLAVA, Alder. 



Name. — From vortex, a whorl, and clava, a genus of hydroids ; so called from the verticillate 



disposition of the tentacles. 



TROPHOSOME. — Htduocatjlus simple, destitute of a conspicuous peeisaec ; 

 HTDKOEiiiz.A. a filiform stolon. Htdkaktii claviform, with two verticils of tentacles ; 

 tentacles composing the proximal verticil filiform, those composing the distal verticil 

 shorter and capitate. 



GONOSOME. — Unknown. 



The genus Vorticlava was founded by Alder for a small hydroid, wliich he discovered in a 

 rock-pool on the coast of Northumberland. It seems to be a well-constituted genus, but as 

 nothing is yet known of the gonosome, we are compelled to regard it as, to a certain extent, 

 provisional. In the form of the hydranth, with its two dissimilar sets of tentacles, there is a 

 strong affinity between Vorticlava and the genera Acharadrimn , Heterodephanus, Stauridium, 

 Cladonema, Hahcordi/le, and Pennaria. The absence of a distinct perisarc, however, separates 

 Vorticlava from all these genera except Heterostephanus. 



1. Vorticlava eumilis. Aider. 



Vorticlava humilis, — Alder, Catal. Zoopli., p. 10, pi. i, figs. 1 — 3. Hincks, Brit. Hydr. 

 Zooph., p. 132, pi. xxiii, fig. 1. 



TROPHOSOME. — Hydrosome attaining a height of about two tenths of an inch, 



' Thougli without the gonopliores, the identification cannot be cousidered as absolute, the 

 resemblance of the trophosomes is so close as to justify our assuming, ^^■ith a certain provisional reserve, 

 an identity of species. 



