MARINE MOLLUSCA OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 347 
species of Margarita. To us, and several other malacologists who have examined it 
with care, it not only appears almost full-grown, but with some confidence is now pro- 
posed to be included in the genus Cyclostrema, at all events provisionally ; for this 
genus is somewhat multifarious already in its component parts, and much needs the 
services of a special monographer. 
The nuclear whorls are, it is true, slightly nepionic, and shapelessly turgid, but the 
penultimate and body whorls are very well sculptured and defined, being acutely spirally 
bicarinate. Around the umbilicus, likewise, a third keel, crenulate, and not so acute, 
revolves. A pale straw-coloured epidermis covers the whole surface uniformly. The 
operculum, for microscopic aid in the examination of which we are much indebted to 
Messrs E. A. Smirx and Rosson of the British Museum (Natural History), is dark red- 
brown, with nucleus not quite central, and multispiral. This we take the opportunity 
also to figure (fig. 22a). 
Calliostoma modestulum, Strebel. 
Calliostoma modestulum, H. Strebel, Schwed. Sudpolar Exped., p. 70, Taf. i. fig. 13 a, b (1908). 
Hab.—Station 346, Burdwood Bank, 56 fathoms, from Sponge. 
‘T'wo very young specimens, trochoid in form, with the upper whorls elegantly 
spirally lirate, we assign to the above name with a little doubt. The original type 
came from the West Falklands, lat. 52° 29’ S., long. 60° 36’ W., dredged at 197 metres 
(SrREBEL). 
With this occurred Photunula expansa, Sowb., and one broken example of a 
beautifully nacreous shell, which, judging from the figure,* may be Calliostoma 
mobiusi, Strebel. Our specimen is more trochoid than photinuloid, though it possesses 
some characters of the latter, and is lightly spirally grooved, these being most con- 
spicuous at the periphery of the body whorl. Dimensions: alt. 10, diam. 12mm. It 
likewise may be compared with Photinula Crawshayz,t Sm., from Christmas Island, but 
the whorls are not ventricose. It is unfortunately somewhat broken; the operculum is 
present, being horny and multispiral. 
Sub-order MONOTOCARDIA. 
(a) Ptenoglossa. 
Family Scalide. 
Scala magellanica, Phil. 
Scalaria magellanica, Philippi, Archiv fiir Naturg., vol. i. p. 65 (1845). 
Hab.—Station 346, Burdwood Bank, 56 fathoms, in Sponge. 
Only very imperfect specimens, either very young or broken fragments; enough, 
however, to identify the species. 
* StREBEL, Moll. der Magalhaen. Prov., ii. p. 133, Taf. v. fig. 22. 
+ Smrru, Proc, Malac. Soc. Lond., vi. p. 335, fig. 2. 
