SERTULARIA ABIETINA. 267 



vary much in length, becoming gradually shorter towards 

 the apex. But every here and there branches are given off 

 of much larger size, which are themselves pinnate, or even 

 bi- and tripinnate, copies, in fact, of the principal shoot. 

 These branches often curiously imitate the growth of the 

 parent stock, one or two only of their pinnae attaining an 

 exaggerated size and exhibiting a composite form. Some- 

 times a very large proportion of the pirmse on the main 

 stem are much elongated, continuing simple for about a 

 third of their length, and then becoming pinnate for the 

 remaining two-thirds. In this way very elegant specimens 

 are formed, which may remind us of the proliferous fronds 

 of some species of fern. 



The capsules are produced in rows along the upperside 

 of the pinnae, and, it would seem, principally in the winter 

 and early spring. The ova are developed into planules 

 within an external marsupium, such as we find in Sertu- 

 larella polyzonias and other species. The embryos are of 

 a bright yellow colour. 



The polypites, which project but little from the calycles, 

 have 26 (or more) short tentacles. 



Hob. On shells, stones, &c. from deep water, very com- 

 mon ; generally distributed. 



Amongst the refuse of the Brixham trawl-boats this 

 species occurs in immense quantity. The nets come up 

 laden with it and its allies S. argent ea and H. falcata, a 

 glorious sight to the naturalist. The trawlers carry on 

 their work chiefly in about 30 fathoms, and at this depth 

 whole tracts of the sea-bottom must be clothed with a 

 luxuriant growth of these elegant corallines. Mr. Peach 

 informs me that at Durness, in Sutherland, S. abietina is 

 often thrown ashore, with a very small admixture of other 

 rejectamenta, by cart-loads, and is used as manure by the 

 Highlanders. 



