OCTINEON LINDAHLI. 479 



beneath thein, and by the [sheaths of the] tentacles between the muscles. 

 Six retractor muscles are shown, and eight [sheaths for] tentacles. The 

 directive muscles are apparently the pair on the extreme right and those on 

 the extreme left of the figure [as there is only one entoccelic tentacle sheath 

 between them. It will be noticed, however, that in order to tally exactly 

 with Fig. 9 only one tentacle sheath should be pointing directly towards the 

 observer instead of two. The right-handmost of these is drawn as a tube, 

 but is perhaps the thick " depressor " muscle of mesentery 3 in Figs. 11 and 

 12. There are in this case only seven tentacle sheaths shown, the same 

 number as indicated by Fig. 9. None of the specimens in my possession 

 were nearly so spacious as the one here figured, but no doubt Dr. Carpenter 

 selected the least flattened and contracted specimens for dissection]. 



PLATE 30. 



These figures are all from my own drawings, and, with the exceptions of 

 Figs. 12 and 23, have been outlined by the camera lucida. The histological 

 condition was so bad that I have represented the body layers diagrammatically 

 (except in Figs. 12 and 23) : — ectoderm blocked, mesoglcea black, endoderm a 

 grey line. 



or. d. Oral disc. 

 ov. Ovary. 

 pe. d. Pedal disc. 

 ?•. m. Retractor muscle. 

 st. Stomodseum. 

 te. Tentacle. 



te. p. Tentacular pouch of oral disc. 

 F. "Ventral" aspect, in the Ed- 

 wardsia nomenclature. 



a. Peripheral plate of mesentery. 



b. Lateral plate of mesentery. 



c. Central plate of mesentery. 



d. Tendon. 



dir. Directive mesentery. 

 D. "Dorsal " aspect, in the Edwardsia 



nomenclature. 

 ext. col. External part of the column. 

 int. col. Inturued part of the column. 



Fig, 11. — Transverse section near the apex of the cone. Internally lies the 

 (broken) inturned part of the column ; towards this radiate the peripheral 

 plates of the twelve primary mesenteries and a few of the lower orders ; from 

 it radiate the short central plates. The section has cut some of the tentacular 

 pouches, exhibiting in two cases the contained tentacles, and has also shaved 

 the upper part of two of the retractor muscles. 



Fig. 12. — Diagram showing the general arrangement of the mesenteries, a 

 description of which will be found on p. 466, et seq. 



Fig. 13. — Part of a section vertical to the animal, and at right angles to 

 the plane of the pedal disc. The inturned part of the column, distinguished 

 by its enormously thick mesoglcea, is cut nearly at a right angle, owing to its 

 flexure below ; in this region its sandy lining is replaced by ectoderm, thrown 

 by ridges of the mesoglcea into six folds. It is seen to open into the tentacu- 

 VOL, 35, PAET 3. — NEW SEK. K K 



