308 
I propose to name this species, the examined fragments of 
whicli are from the Albatross’ station 2015, Sertularia extensa n. sp. 
In some young colonies of H. falcata from Hellebael, Den- 
mark, which have a length of 29 mm I have also found a proximal 
portion with shorter internodes and provided with 8—13 pairs 
of rather short alternate branches, but these internodes differ from 
the corresponding in H. plumulifera therein, that they are onl\ 
provided eacli with an axillary hydrotheca. In the youngest of 
these colonies the distal portion, which bears a few rudimentary 
branches, has a length of 10 mm. 
To the present genus may perhaps still be referred Sertula- 
rellci limbata Allm.*). 
Odontotheca n. g. 2 ). 
The aperture is provided with two strongly developed, some- 
times unequal abcauline teeth, between which there are found a 
much larger and deeper adcauline and a mucli smaller abcauline 
sinus. In each sinus is fixed a thin opercular membrane, which 
ends in a straight edge, and, therefore, lacks a free valvular portion. 
In a few cases there is found a median adcauline tooth, and in 
such species (f. inst. in O. trispinosa Cought) the adcauline mem¬ 
brane is angularly bent, and the abcauline provided with a free 
valvular portion. The gonothecae have a very variable habitus, 
being either srnooth, ringed or provided with tw r o spines. 
To this genus I must refer the following species: Sertularia 
operculata L. (22.), S. aperta Allm. (4.), S. minima d’Arcy Th. (4.), 
S. unilateralis Allm. (4.), S. crinis Allm. (4.), S. crinoidea Allm. 
(4.), S. megalocarpa Allm. (4.), S. bispinosa Cray (7.), S. Maple- 
stonei Bale (7.), S. macrocarpa Bale (7.), S. pulchella d Arcy Th. 
(7.), S. Videns Bale (7.), S. trispinosa Cought (7.), Sertularella tro- 
chocarpa Allm. (4.), Sert. episcopus Allm. (2.), Sert. rectitheca Ritchie 
(50.), Thujaria ramosissima Allm. (4.), Th. plumosa Clark (44.) and 
Abietinaria greenei (Clark) (44.). 
i) 4. 2 ) PI. V, ligs. 8—15. 
