FROM THE LAGOON AT FUNAFUTI. 201 
fathoms); sample 7 (24 fathoms); sample 10 (26 fathoms) ; 
sample 11 (25 fathoms); sample 13 (26 fathoms); sample 14 
(16 fathoms) ; sample 16 (20 fathoms) ; sample 17 (12 fathoms) ; 
sample 18 (74 fathoms). 
POLYTREMA MINIACEUM (Pallas), var. ALBA, Carter. 
Polytrema miniaceum, var. album, Carter, 1877, Ann. Mag. Nat. Hist. 
ser, 4, vol. xix. p. 215, pl. xiii. fig. 14. 
This variety is generally rare at Funafuti. 
Lagoon, Funafuti. Sample 1 (10 fathoms); sample 2 (153 
fathoms); sample 7 (24 fathoms); sample 13 (26 fathoms). 
PoLyTREMA PLANUM, Carter. (PI. 20. figs. 6, 7.) 
Polytrema planum, Carter, 1876, Ann. Mac. Nat. Hist. ser. 4, vol. xvii. 
p- 211, pl. xiii. figs. 18, 19. [Immature growth.] 
Gypsina melobesioides, Carter, 1877, ibid. ser. 4, vol. xx. p.172. [Full- 
grown form, description only. | 
G. melobesioides, Carter, 1880, ibid. ser. 5, vol. v. p. 445. 
Polytrema miniaceum (Pallas), var. znvelva, Chapman, 1900, Journ. 
Linn. Soc., Zool. vol. xxviii. p. 17, pl. 2. fig. 3, and text-figure 2. 
P. planum, Carter, Chapman, 1901, Ann. Mag. Nat. Hist. ser. 7, 
vol. vil. pp. 82, 83. 
In my earlier description of the Funafuti specimens, this 
particular form was regarded as a variety of the common 
branching type of P. miniacewm, which is distinguished by its 
red colour. Since then I have found abundant specimens of 
P. planum of very extensive growth on rough reef-specimens 
from the same collection, which show that the affinities of 
P. planwm are rather towards the white variety of P. miniacewm, 
var. alba, Carter; for in the fresh specimens its test is often of 
snowy whiteness, not unlike, as Carter remarks, the sugar- 
coating on a bride-cake. The cemented reef-specimens are often 
discoloured or yellowish in their tint, but never pink or rose- 
coloured. 
It is exceedingly difficult in some cases to distinguish 
P. planum from certain encrusting plants such as Lithothammon 
and Lithophyllum; and indeed the only distinctive character 
between Lithophyllum onkodes and P. planum, when viewed 
externally, is the presence of the little granular conceptacles 
often, but not always, to be seen studding the surface of the forms. 
Carter’s original description and figure dealt only with a 
young or immature growth, but a comparison between the type- 
specimen of the so-called Gypsina melobesioides at the Natural 
