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301 
portion, and the egress of the hydranth takes place only through 
the fissure between the edges of the two membranes. In this 
species, therefore, the opercular apparatus is formed as the walls 
of'an "AP ent 
Å single colony was taken at lat. 429'N, long. 130? 30” E. by 
Capt. E. Suenson. Depth 60 fathoms. 
This species is nearly related to S. Fabricii Lev. which also 
lacks a median adcauline projection, but in' the latter species the 
adcauline membrane is not sloping outwards, and being, besides, 
slightly convex from side to side the abcauline membrane is 
provided with a feebly developed free valvular portion. 
Sertularia decipiens n. sp. 
(Pl. IV, figs. 11, 12). 
The colonies, the largest of which attains a height of 
22 mm, are singly pinnate with alternate branches, and the stem 
is divided into regular internodes, each of which as a rule bears a 
single branch. An exception is found in the lowermost branchiferous 
internode which always bears two opposite or subopposite branches, 
and in a småll number of the colonies examined the same is the 
Case with still another internode, in a single colony even with two. 
While the furrows dividing the single internodes from each other 
are as a rule sloping very little towards the frontal surface of the 
colony, those bounding the proximal end of the internodes with 
two branches are very different from the others, being very long 
and deep and the two lateral halves of each forming with each 
other two acute angles of about 359—40?, a distal on the dorsal 
and a proximal on the frontal surface of the colony. The lower- 
most =non-branchiferous portion of the colony has the length of 
3—4 internodes, and as a rule is not divided into distinct inter- 
nodes, but in a small number of the colonies the distal end presents 
1—2 short internodes, the proximal end of which is bounded by 
similar characteristic furrows as those above mentioned. The 
branches, of which the largest colonies bear 8—9 on each side, 
