112 NATURAL HISTORY OF 



arterial blood-colour. It is the stoutest and most rigid 

 of all our native Sertularid^." 



7. D. ALATA, Hincks. 



Sertularia alata (McA.). 



Hab. : Shetland, Hebrides (A. M. K), Falmouth 

 {Cocks), Cornwall {Peach). Height 3 — 5 in. 



Described in the Annals and Magazine of Nat. Hist, 

 for February, 1855. 



Colour blackish-brown with a highly polished appear- 

 ance. Stem pinnate. Branches alternate. Calycles 

 small, the free portion abruptly standing out from the 

 stem. 



Genus III. Sertularia, imwoews (iw pari). 



Zoophyte plant-like. Stems more or less branching, 

 jointed, rooted by a creeping stolon. Hydrothecce bi- 

 serial, opposite or alternate, without external opercu- 

 lum. Gonothecce scattered, with a simple orifice and 

 without an internal marsupium. — T. H. 



1. S. PUMiLA, Linn. Plate YII. fig. 1. 



S. piccina {D. Chiage), Dynamena pumila {Lamx., 

 Mem., Ag.), D. naine {De B.). 



Hab. : Common. Height generally about \ in. 



This common zoophyte is found as a parasite on fiici, 

 which are sometimes almost covered by its dense 

 growth. The calycles are opposite, and the appear- 

 ance of the zoophyte is tliat of a number of Vs or 

 inverted triangles strung together. Between each pair 

 of calycles is a joint, which divides the stem into short 

 internodes. The occurrence of this joint, however, 

 varies considerably. It is often more or less, some- 

 times entirely, obliterated, and often occurs between 

 each two pairs of calycles. If an internode in a Sertu- 



