480 PEOFBSSOE, G. J. ALLMANN ON THE HTDEOIDA 



ramification is, like that of all the true Plumularice, singly pinnate, while it is exceptional 

 only in the opposite instead of alternate arrangement of the pinnee or hydrotheca-bearing 

 ramuli. 



A rather striking feature of Biplopteron insigne consists in the ramiilus which each 

 of the ultimate pinnae gives off near its origin. This ramulus, which usually bifurcates, 

 consists of slender elongated internodes, each bearing a hydrotheca and nematophores 

 quite like those of the pinnae. The gonangia form two closely set alternating series 

 running along the front of the rachis and along that of the primary pinnae from the base 

 to the apex. 



Biplopteron insigne, when living, must be a singularly beautiful object, while the great 

 development of the nematophores must especially fit it for the observation of the characte- 

 ristic phenomena of these bodies. Indeed the spirit-specimens examined were to a great 

 extent enveloped and obscured by irregular filaments and masses of a granular mucus- 

 like substance, which I have no doubt are the remains of the pseudopodial extensions 

 from the protoplasmic contents of the nematophores. It was dredged off the south-west 

 coast of Spain, from a depth of 3G4 fathoms. 



DESCRIPTION OF THE PLATES. 



PLATE LXV. 



Fig. 1. Thuiaria laxa, natural size. 



Fig. 1". Thuiaria laxa, portion of hydrothecal ramulus magnified. 



Fig. 2. Thuiaria hippuris, natural size. 



Fig. 2". Tlmiaria hippuris, portion of hydrothecal ramulus magnified. 



Fig. 3. Thuiaria salicornia, natural size. 



Fig. 3". Thuiaria salicornia, a portion magnified. 



PLATE LXVI. 



Fig. 1. Lafo'ea halecioides, natural size. 



Fig. 1°. Lafo'ea halecioides, a portion magnified. 



Fig. 2. Biphasia coronifera, natural size. 



Fig. 2". Biphasia coronifera, a portion magnified. 



Fig. 3. Sertularella gayi, var. robusta, natiu-al size. 



Fig. 3". Sertularella gayi, var. robusta, a portion magnified. 



PLATE LXVII. 

 Fig. I. Aglaophenia dromaius, natural size. 

 Figs. 1", 1'. Aglaophenia dromaius, portions of hydrothecal ramuli magnified. 



