70 THÉEL, NORTHERN AND ARCTIC INVERTEBRATES .I. SIPUNCULIDS. 
blance both in habit and general structure. However, a careful examination has re- 
vealed that this is not the case, but that it is distinguished by several characters of 
importance. Thus, for instance, the skin presents a different structure, being covered 
with minute granulge and without true papille (Figs. 15—18). Moreover, the ten- 
tacles are considerably more numerous and arranged in another manner. Unfortu- 
nately they are drawn within the body together with a portion of the proboscis, 
their true arrangement bemg difficult to define (Fig. 189). 
Among all known forms of Phascolosoma the new species may possibly be the 
nearest related to the Ph. Hanseni of DANIELSSEN and KOREN. Nevertheless, pre- 
suming that the information given by the two investigators named is correct, we 
ought to find some important marks of distinction existing between them. Having 
had at my disposal for inspection only some fragmentary types. kindly sent to me 
by Dr APPELIÖF of Bergen, I am unable to verify their statements in all respects. 
In consequence of this, the two forms in question had better be kept separate until 
further investigation has been made. In this view I am strengthened by the fact, 
that the two forms live in such very distant localities and under such very different 
conditions. 
Phascolosoma procerum MöBrtuvs 1875. 
Pl. II. Figs. 19—26, P1. III. Figs. 27—28, Pl. XIII, Fig. 190. 
Phascolosoma pyriforme "PTRÉEL 1875. 
Habitat: 
West Coast of Sweden: Styrsö, 20—35 fms (OLSSON 1869) 1 sp.; Dyngö 9 fms 
(Gois 1862) 4 sps.; Lindö (OLSSON 1869) 3 sps.; Väderöarne, 15 fms. (Gois 1862) 
3 sps.; Gullmarn, at almost all points, with a bottom of mud or clay, 10—20 fms.; 
they are not very common in the Gullmarfjord, but during a day's work the dredge 
brings up from 6 to 10 individuals (Marine Biological Station Kristineberg); 57” 46' 6” 
n.—10” 5' e., Torreboskär—Skagen, mud, 22 fms. (Gunh. Exp. "/; 1878. 5 sps.; 57” 37 
8" n.—10” 53' 8" e., Skagen Nidingarne, blue mud, 17 fms. (Gunh. Exp. '/; 1878), I sp. 
Distribution in General: 
MöBivs has dredged up some specimens in the North Sea at the Bass Rock, 
in the neighbourhood of Edinborough, which proves that the species in question has 
a wide distribution in the northern seas. But it is by no means an arctic form. 
The species in question was described simultaneously, or at least in the same 
year, by MöBrus and myself. Judging from the fact that the diagnosis of MÖBIUS 
is printed on page 157 of the "Jahresbericht der Commission etc.', which carries 
the year 1875 on its title-page, it seems probable that my own paper, published in 
the spring of the same year, is of an earlier date. Be this as it may, the name ""proce- 
rum" of MöBIuS must be kept, because I wrongly supposed that my form was iden- 
tical with the Phascolosoma pyriforme of DANIELSSEN 1859, a mistake easily explained 
by the incompleteness of his description — a few lines without any figures. 
