38 AXTEXXELLA GRACILIS. 



AXTENELLA Allman nov. gen. 



Gexeric Character. — Trophosome. — Hydrocaulus consisting of simple 

 stems, which spring from a congeries of tubular filaments ; stems divided 

 into internodes, destitute of pinnae, and directly bearing the hydrothecae. 

 Hydrothecae with entire margin. Xematophores free and movable. 



Gonosome not known. 



If in a true Plumularia the rachis had never been developed, and the 

 pinnae had thus come to stand immediately on the hydrorhiza, we should 

 have a form with the essential characters of Antennella. 



Antennella gracilis. 

 PL XXII. F'kjh. 6, 7. 



Trophosome. — Hydrocaulus attaining a height of about an inch, simple 

 or with an occasional division near its base, springing in dense tufts from 

 a mass of creeping, tortuous, inosculating, and entangled filaments, divided 

 into internodes by very oblique joints, and with an intervening obscure hori- 

 zontal joint, also generally apparent. Hydrothecae borne along the hydro- 

 caulus from its distal end to within a short distance of its base, rather large, 

 cylindrical, deep, with a circular margin, free for about half their height. 

 Supracalycine nematophores borne each on the extremity of a long hollow 

 process which flanks the hydrotheca on each side ; mesial nematophores 

 usually four between every two hydrothecse. 



Gonosome not known. 



Dredged off Carysfort Reef from a depth of 60 fathoms. 



A form nearly allied to the Antennella gracilis of the present Report has 

 been dredged off the British coast by Hincks, who regards it as a variety 

 of Plumularia catharina Johnston, and believes it to be identical with the 

 Aniemuihuia cf/athlfcra of Dana, and witli the Sertularia secundaria of Cavolini. 

 That all these ))elong to the form for whicli I have constituted the genus 

 Antennella, there can, T tliink, be little «loubt. 



Througiiout that section of the Plumularid;© which is characterized by 

 its in()val)le nematophores, and of whicli Plumularia setacea may be taken 

 as the type, the modifications of ramification as expressed in the disposition 

 of the hydrothecal or ultimate ramuli admit of being thrown into a series 

 whose members present a definite relation to one another. 



Taking as our point of departure such forms as Plumularia setacea of 



