THÉEL, NORTHERN AND ARCTIC INVERTEBRATES. I. SIPUNCULIDS. 
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The trunk is more or less cylindrical, often slightly wider towards the posterior 
extremity. Anteriorly it passes gradually into the proboscis, which has about the 
same length as the trunk itself (Figs. 60 and 67). On an average the total length 
amounts to 45 mm. The body-wall is smooth, hyaline and transparent, the intestinal 
spiral being visible through it. In several specimens the proboscis-base and the po- 
sterior extremity of the trunk have the colouring of rust. The glands of the skin 
(Figs. 66 and 68—70) are minute, invisible to the naked eye and slightly more crowded 
posteriorly; they appear to be devoid of true papille. The tentacles (Figs. 61—64 
and Figs. 204—205) are highly reduced and replaced by low protrusions of the oral 
disk, which present a certain regularity in their arrangement. In one specimen, 
from East Greenland (74” 52 n.—17” 16 w.), which was fully extended, the tentacles 
presented themselves as five distinct lobes. 
As a rule, the animal is armed with hooks (Figs. 61, 63. 65). In a very few 
cases these are wholly absent. Between them and the tentacular erown a quite 
smooth space is visible. The hooks are seldom crowded but rather the contrary. 
The rule is that they are more or less scattered. The retractor-museles are two in 
number, webbed together anteriorly, and embracing the nerve-cord with their rather 
long roots, which are attached to the body-wall slightly behind the middle of the 
trunk. Two free segmental organs are present. The intestinal spiral is unattached 
posteriorly and is composed of about 22 double twists. The reproductive organs form 
festoons at the bases of the retractors and the body-cavity is often filled with ova. 
Phascolion strombi (Monrt. 1804). 
Pl. VI. Figs. 82—95, Pl. VII. Figs. 109; 110, Pl. XV. Figs. 207, 208. 
2? Phascolosoma cementarium (QUATREF. 1865) VERRILL 1873". 
2 Phascolosoma tubicola VERRILL 1874". 
2 Phascolion tubicola SELENKA 1883 and 1883. 
2 Phascolion ccementarium SELENKA 1883. 
Phascolion spetsbergense THÉEL 1873. 
Habitat: 
Newfoundland: 52” 25 n.—52” 12 w., clay mixed with sand, 162 fms. (Ing. & 
Gl. Exp. '/s 1871), 6 sps. — 52” 3 n.—52” 19 w., clay and sand, 161 fms. (Ing. & 
GL UESp: "7; 1871), P sp: 
West Greenland: 72” 20 n.—59” 39 w., clay with stones, 172 fms. (Ing. & Gl. 
'"/, 1871), 2 sps. — 63” 35 n.—52” 57' w., sand and gravel. 43 fms. (Ing: '& GE 
1871), 1 sp. — Umanak, clay, 200 fms. (Amondsen), 8 small light sps. — Julianehaab, 
1 Report on the condition of the sea-fisheries at the south coast of New England in 1871 and 1872. 
Washington 1873. 
? American Journal of Science and Arts. Ser. 3. Vol. 5. New Haven 1871, and Proceed. of the 
American Association, Meet. 22. Salem 1874. 
