REPORT ON THE PENNATULIDA. 13 



Family 3. Anthoptilid.^. 



Antlioptilum, u. gen. 



Polypidom without leaves, of the general appearance of Funiculina. Polyps in many 



short rows on the sides of the rachis, large, without cells. At the lower end of the rachis no 



prolonged streak of undeveloped polyps. Zooids lateral, ventral, and dorsal, all of one kind, 



small, wart-like. Axis round. No calcareous corpuscles, except at the end of the stalk. 



1. Anthoptilum tJwmsoni, n. sp. (PI. V. figs. 16-18). 



A large, magnificent sea-pen, with a short, thick stalk, long feather, and long polyps 

 crowded eight to ten in one row. Polyps often united at their bases. Zooids very 

 numerous. Eachis free only on the ventral side. 



Stalk with a thick swelling at the upper part, and a smaller end-bidb, with short 

 pointed free end. 



Polyps very long, without cells, and with long tentacles very seldom retracted. 

 These polyps are disposed in many oblique rows on both sides of the rachis, so as to 

 cover more or less completelj' its dorsal aspect. In the higher parts of the rachis it is 

 quite impossible to find a free surface on this side, whilst the reverse is the case below in 

 the neighbourhood of the stalk. On the other side the ventral surface of the rachis is 

 free in its whole length. With regard to the position of the polyps, I have fm'ther to 

 remark that very often the lowest parts of two, three, or more of them are united 

 so as to produce the appearance of very small pinnules, shorter even than those of 

 Pavonariajimnarchica, but in no place are all the polyps of one row united in such a 

 manner. The tentacles of the polyps are very long, and provided with long, slender 

 branches (pinnules), which are remarkable from their moniliform appearance (fig. 18), 

 and the great number of small thread-cells situated in their single protuberances. 



The zooids of Anthoptilum thomsoni are very numerous. The principal are lateral, 

 and lie between the rows of polyps ; but these lateral zooids reach everywhere the 

 ventral surface of the rachis, and in many places the single lateral rows coalesce there 

 so as to form genuine ventral zooids. This coalescence, however, never takes place on 

 the greater part of the rachis, and generally coalesced lateral zooids alternate vnih 

 separated sets. On the dorsal side the zooids avoid the middle line where this fine is 

 free of polyps, but where the polyps cover the whole dorsal surface the zooids are also 

 to be found everywhere. A peculiar feature of this sea-pen is that in many places little 

 groups of zooids reach as far as the base of the polyps themselves, and are also found 

 between the individuals of one row. The size of the zooids is from 0"40 to 0"58 mm., 

 and their structure the ordinary one, inasmuch as they possess two well-developed 

 mesenteric filaments. With regard to the colour of Anthoptilum thomsoni, some sjsecimens 

 are totally uncoloured ; others have all the polyps more or less brown, the stalk and 

 rachis on the contrary colourless. 



