118 CATALOGUE OF THE ZOOrHYTES OF 



A more reliable character will be found in the number of joints 

 in the branchlets. In A. antennma there are always two joints 

 between the cells throughout; in A. ramosa only one on the 

 lower and principal part of the branchlet, increasing to two neai- 

 the top. The internodes in the latter species are also longer and 

 straighter, as may be seen in the magnified figures in " British 

 Zoophytes," t. xix. and xx., where the tubules are likewise repre- 

 sented in each, though the number is deficient. In perfect spe- 

 cimens these are arranged in the following order : — 1 below the 

 cell, 2 abreast at the upper angle of the cell, and 1 at a little 

 distance above: this last is on the same internode in A. ramosa^ 

 and on the intervening or non-cellifcrous internode in A. antennina. 

 Besides these, there are two large tubules (one on each side) at 

 the base of the branchlets, where they join the stem; and in A. 

 ramosa^ two smaller ones in front and one a little way up the 

 stem. I have not observed these latter in A. antennina^ though 

 they may possibly be found in luxuriant specimens. 



A. ramosa, then, may be distinguished from A. antennina by 

 its branched stem, and by the branchlets being long, straight, 

 and tapering, with only a single joint between the cells for the 

 greater part of their length. The branchlets of A. antennina are 

 short, stunted, and curved inwards, with two joints between each 

 cell throughout. 



12. PLUMULARIA, Lamarck. 



1. P. FALCATA, Linn. 



Johns. Brit. Zooph., 90, t. xxi., f. 1, 2. 

 On shells and stones in the coralline zone, and in deep water ; 

 very common. 



2. P. cmsTATA, Lamh. 



Johns. Brit. Zooph., 92, t. xxiii. f. 1 — 3, and wood- 

 cut 16. 

 A single specimen has been found on Fucus siliquosus in Whit- 

 bum Bay, by Miss Dale. 



3. P. FINN AT A, Linn. 



Johns. Brit. Zooph. 95. t. xxi. f. 4, 5. 



