1889.] RARE SPECIES OF PLEXAURIDS. 49 
The present species is erect, branching, elegant, not at all closely 
bushy ; there is no spreading base, but the trunk is rather wide, 
being about 3 cm. in diameter; the branches are flattened at the 
points of bifurcation; the secondary trunks give rise to branches, 
which do not ordinarily branch more than five times, so that many 
of the terminal twigs are as much as 35 cm. long; these terminal 
twigs are about 5 mm. in diameter. There are a few nodosities. 
The cortex is fairly thick, the calyces numerous, irregularly scattered, 
rather large pits, so that the general appearance is not unlike that 
of P. porosa. Axis brownish, impregnated with calcareous salts, 
and the species belongs, therefore, to the genus Plewaurella and not 
to Plexaura. The characteristic spiculation is shown in the accom- 
panying figure. 
Hab. West Indies. 
5. PLEXAURELLA VERMICULATA. (Plate IIT. fig. 5.) 
Gorgonia vermiculata, Lamk. 
Plexaura vermiculata,Val.; see Milne-Edwards & Haime, Corall. i. 
lb O: 
: Plexaurella vermiculata, Kolliker, Icon. Histiol. p. 138. 
There is not, I think, sufficient reason for distinguishing as the 
type of a distinct species a specimen labelled by Dr. Gray as Plexvaura 
porosa, but which is certainly a Plewaurella, inasmuch as it has 
deposit of calcic carbonate in its axis. It presents some slight points 
of difference from P. vermiculata, as described by Milne-Edwards 
and Haime, and there is not an absolute identity of spiculation. 
There cannot, I think, be any doubt that there has been a tendency 
to neglect the variations possible in these forms, and it is better to 
refrain from “ splitting” species. 
In the specimen under consideration the calices are nearly as 
ciosely packed as in P. porosa; the terminal branches are often 
rather less than 8 mm. in diameter, and the main trunks are from 
12 to 16 mm. across, whereas Milne-Edwards gives 8 mm. for the 
former and 9 to 10 mm. for the latter; no statement, however, is 
made as to the height of the whole mass; in the case of the British 
Museum specimen it is rather more than 60 cm. and all the tops are 
a little broken off. 
The cortex, which is thick, is of a lightish brown colour; the axis 
is of alight brown colour. The axis is flattened at the angles cf 
division, and there appears to be no tendency to the formation of 
nodes ; some of the terminal branches are more than 15 em. long. 
The spicules are, as the figures show, short, but somewhat irregular 
in form. 
EXPLANATION OF PLATE III. 
Spicules of Plexaura and Plexaurella, x 180. 
Fig. 1. Plexaura principalis, p. 47. 
2. Plexaura suffruticosa, p. 48. 
3. Plexaurella affinis, p. 48. 
4, Plexaurella anguiculoides, p. 48. 
5. Plexaurella vermiculata, p. 49. 
Proc. Zoot. Soc.—1889, No. IV. 4 
