68 MR. A. W. WATERS ON 
opening seems to be a chitinous ring in Lepralia sincera, Sm., 
from which there are rays of muscular tissue, and there are 
concentric rings, also no doubt contractile. 
Pergens * speaks of the tentacular sheath having four close- 
able openings: (1) the opercular opening, (2) Nitsche’s diaphragm, 
(3) oral opening, (4) anal opening; but this seems to me more 
complicated than is the case, and though the diaphragm may in 
some cases be a little distance from the external opening, yet 
it seems enough to speak of the opening through the diaphragm 
and the anal opening ; and I cannot follow Pergens in considering 
that any opening has been found from the tentacle-sheath into 
the body-cavity. 
Myriozoum ovum, Smitt, will be Stichoporina or Fedora; and 
M. marionensis, Busk, is the only species determined as Myriozoum 
from the Southern hemisphere. 
24. Myriozoum coarctum (Sars). (Pl. 9. figs. 2, 3.) 
Cellepora coarcta, M. Sars, Nyt Mag. f. Natury. vol. vi. p. 148 (28), 
1850? 
Leteschara coarcta, M. Sars, Beskr. N. Poly. 1862, p. 155 (17). 
For synonyms of Smitt, Busk, Hincks, Lorenz, see Miss Jelly’s 
Catalogue. 
Myriozoum coarctum, Bidenkap, Bryozoen von Ost-Spitzbergen, Zool. 
Jahrb. vol, x. p. 621; Hennig, Cifvers. af K. Vetensk.-Ak. Forh. 1896, 
p- 397. 
This species does not appear to have been figured, saving the 
section given by Smitt. The semicircular avicularia are placed 
in a row between the zoccia and vary considerably in size, so 
that the avicularian aperture may be as large as the oral aperture. 
There are 16 tentacles, as in MZ. subgracile, d’Orb., while in 
M. truncatum, Pall., there are about 26 or 27 tentacles. Pergens 
speaks of 33, but I have not seen so many, and sections he sent 
me correspond with those I made from material brought back 
from Naples. One of the pieces is about two inches long, and 
has clearly been broken off a much larger one. The branches 
anastomose at an angle of about 60 degrees and more, and some 
branches grow out nearly at right angles from the main branches. 
Loc. Spitzbergen, 19-80 fath. (Smztt), 40-95 fath. (Bidenkap) ;. 
Kola, Norway; Jan Mayen, 140-400 metres (Lorenz); Davis 
* “Untersuch. an Seebryozoen,” Zool. Anzeiger, 1889, p. 4. 
