124 THÉEL, NORTHERN AND ARCTIC INVERTEBRATES. I. SIPUNCULIDS. 
Plate Xl. 
a. anus. — de, coils of the intestine running downwards. — dr. dorsal retractor. — e. eggs. 
— fm. fixing muscles. — g. genital festoons. — i. intestine. — mm. mesenterie membrane. — 
ne. nerve-cord. — oe. oesophagus. — s. segmental organ. — sm. spindle muscle. — ue. coils 
of the intestine running upwards. — vr. ventral retractor-muscle. 5 
Fig. 173. Phascolosoma eremita (M. SARS). + Mosselbay. 
Fig. 174. Phascolosoma margaritaceum (M. SARs).. +. 75? n.—113? 30' e. 
Fig. 175. Phascolosoma Sabellarie n. 2. Gullmar Fjord. 
Fig. 176. Phascolosoma Sabellarixe n. 12. Gullmar Fjord. 
The retractors are attached further back than in the preceding specimen. 
Fig. 177. Phascolosoma improvisum n. 22. Gullmar Fjord. 
'The retractors are attached far behind on the transition between the second and posterior 
thirds of the trunk. 
2 
Fig. 178. Phascolosoma improvisum n. 1?. Gullmar Fjord. 
The retractors are defective in this specimen, the right one not having come to develop- 
ment, and the left one having an abnormal attachment at the posterior end of the body. 
The intestinal spiral is, furthermore, deformed. 
Fig. 179. Phascolosoma improvisum n. 2. Gullmar Fjord. 
The retractor-muscles are attached in the anterior fourth part of the trunk. 
Fig. 180. Phascolosoma improvisum n. 12. Gullmar Fjord. 
The retractors are anomalously attached near to the posterior extremity of the body. 
Fig. 181. Phascolosoma improvisum n. 2. Gullmar Fjord. 
The retractors have a normal attachment near the middle of the trunk, but they are 
united together so as to almost form one whole with two short roots embracing the 
nerve-cord. 
Fig. 182. Phascolosoma improvisum n. 12. Gullmar Fjord. 
The internal organisation normal. 
