PLUMULARIA PINNATA. 295 



We know little of the geographical distribution of this 

 genus. It has representatives in North America; one or 

 two, at least, of our British species range to the Mediter- 

 ranean, and one has been found in Van Diemen's Land. 

 In the extreme north of Europe, both this and the pre- 

 ceding genus would seem to be sparingly developed, if not 

 altogether wanting ; for they are not recorded by Sars as 

 occurring in Norway, nor do they find a place in M orchis 

 list of Greenland Hydroids. 



1. P. PINNATA, Linnaeus. 



SERTULARIA PINNATA, Linn. Syst. 1312; Ellis $ Suland. Zoopk. 46. 

 AGLAOPHENIA PINNATA, Lamx. Cor. flex. 172. 



PLUMULARIA PINNATA, Lamk. An. s. Vert. (2nd ed.) ii. 164 ; Johnst. B. Z. 95, 

 pi. xxi. figs. 4, 5 ; Agassis, N. H. U. S. iv. 358. 



Plate LXV. fig. 1. 



SHOOTS clustered, tall, white, or of a pale horn-colour ; STEM. 

 straight, jointed irregularly; pinnae alternate, several on 

 each internode ; HYDROTHEC^E rather distant, wide, with 

 an entire rim, separated by a sinyle, somewhat oblique 

 joint ; NEMATOPHORES sessile, very minute, one below each 

 calycle ; GONOTHEC^E forming a double row along the 

 main stem, rudely ovate or pear-shaped, shortly stalked, 

 and with a number of spinous projections at the top. 



P. PINNATA sometimes attains a height of seven, and 

 commonly of four, inches; it also occurs of much 

 humbler gowth, rising only to one and a half inch or 

 two inches. It is distinguished from P. setacea by its 

 more robust habit and larger size, as well as its minute 

 structure. The calycles of P. pinnata are only separated 

 by a single joint, those of P. setacea by two. Several 

 pinnae usually spring from each segment of the main stem ; 



