510 FUNAFUTI ATOLL. 
for the young of a Spondylus, hence the erroneous statement on 
p. 402, that the Brachiopoda were absent from the Archipelago. 
The genus 7’hecidea dates back from the opening of the Mesozoic, 
and is manifested in numerous species through a long range of 
formations. Like Nautilus and T’rigonia, it now only survives in 
a few rare and restricted species. It is an interesting coincidence 
that a genus so intimately associated with fossil coral reefs in 
Europe, should recur alive on a Pacific Atoll. So far but two recent 
species, 7’. mediterranea, Risso, and 7’. barretti, Woodward, have 
been detected. The former, for which the subgenus Lacazella has 
been proposed by Munier Chalmas, is unlike the Pacific species ; 
whereas the latter and the West Indian 7. barrett: are quite 
close. These conform neither to Thecidea, as restricted by Hall 
and Clarke,* nor to the various subgenera admitted by them. 
That generic term has been here used in the wider application of 
Davidson. 
On comparing examples of 7. maxilla with the published 
accounts of 7’. barretti, | conclude that the characters are so 
variable that a large series of each will be necessary to discriminate 
properly between them. At present I would point to the flanges 
of the median septum and to the greater development of the 
brachial lamelle, as features possessed by Z. maaxifla but not 
by Z. barretti.t The former, indeed, reminds one of a split 
walnut. 
IT am in doubt whether a pseudo-deltidium exists in 7’. barretta, 
for Davidson writest that ‘in external shape it cannot be 
distinguished from the Mediterranean species,” which has the 
pseudo-deltidium ; and in a small drawing§ he indicates the 
pseudo-deltidium. But, on the other hand, in the enlarged draw- 
ing, || on which I place more reliance, it is not depicted. Again, 
it is not shown in his first illustration,{] nor is it mentioned in 
either description. Should a pseudo-deltidium be absent in 7’. 
barretti, as it certainly is in 7. maxilla, that would isolate these 
two from the remainder of the genus. 
Another feature in common is the fork which projects in two 
slender prongs between the cardinal teeth in both species, and 
strikingly differs from the spoon-shaped processes of 7’. medi- 
terranea and from the three prongs of 7’. radiata, the type of the 
genus. 
* Hall and Clarke—47th Ann. Report New York State Mus., 1894, 
pp. 1091 - 1093. 
+ Dall—Bull. Mus. Comp. Zool., xii., 1886, pl. vi., fig. 2. 
t Davidson—Trans. Linn. Soc., Zool. (2), iv., 1889, p. 162. 
§ Davidson—Loc. cit., pl. xxili., fig. 9a. 
|| Davidson—Loce. cit., pl. xxiii., fig. 10. 
{ Davidson—Geol. Mag., i., 1864, pl. ii., fig. la. 
