66 THÉEL, NORTHERN AND ARCTIC INVERTEBRATES. I. SIPUNCULIDS. 
For several reasons mentioned below, I distinguish between a Forma occidentalis 
and a Forma orientalis. 
»Forma occidentalis.> 
Habitat: 
Spitzbergen: Mouth of Ice Fjord (Sp. Exp. 1898), 2 fragmentary specimens. 
General Distribution: 
Arctic Sea: 70” 54' n.—8” 24 w., 70” 5l' n.—8” 20' w., black sand and clay, 
128 m., and 71” 42 n.—37” 1' e., clay and stones, 271 m. (Mus. B. and Mus. Chr.), 
two incomplete specimens and several fragments. 
In one of the fragmentary types (70” 51 n.—8” 20 w.) at my disposal the 
tentacle-cerown was left in such a condition, that it was possible to make a sketch of 
it (Fig. 191). This was very favourable, because DANIELSSEN and KOREN have 
attached great importance just to the arrangement of the tentacles and, mainly on 
them, they founded their new genus Stephanostoma. Their short generic characte- 
ristic runs thus: "Oral disk exceedingly broad, bearing 10 large tentacular groups, 
dispersed between which are a few isolated tentacles. Anal opening immediately 
posterior to the base of the proboscis.” And in the species-description they write: 
"The position of the tentacles on the buccal disk is peculiar, the collar itself being 
remarkably waved, forming as it does a series of undulations, 10 long (festoons) and 
10 short, Figs. 22, 23." How are we to understand these statements, which do not 
agree with my own experiences? On comparing my figure (191) with those given by 
DANIELSSEN and KOREN scarcely any resemblance will be found between them. 
An examination of my figure (191) displays that, between the 10 large tentacular 
festoons, smaller ones are situated of secondary range, and that the disposition of 
the latter deviates from the description given by the two Norwegian investigators. 
Thus, the interesting facts appear: that in each of the interstices between the 
large median ventral festoon and the nearest large ones only rudiments of festoons 
of secondary range are present, in the shape of a single tentacular prominence, that 
again, in each of the interstices on either side of the large median dorsal festoon 
there are three small festoons of secondary range, one rudimentary, composed of 
two tentacles and two more developed, made up of four tentacles, and, finally, that 
in each of the remaining interstices only one small festoon is to be observed, com- 
posed of four tentacles. Consequently, we have before us a whole series of develop- 
mental stages of tentacular festoons, the larger being the oldest. The smaller ones 
protrude later, somewhat irregular and become more complicate by degrees, in pro- 
portion to the growth of the animal. The older the animal is, the greater is the 
number of the tentacles and the deeper become the festoons or undulations, in order 
to give place for new outgrowing tentacles. That being so, it becomes evident that 
the tentacular erown must have a different aspect under different developmental stages 
of the animal. With regard to Fig. 23 given by DANIELSSEN and KOREN I can only 
say it remains a mystery to me. 
