30 AUSTRALASIAN ANTARCTIC EXPEDITION. 
the youngest being in the Magelliform stage. The chief peculiarity of the series lies 
in the obliquity of the attachment of the jugal band in the Terebratelliform stage, and 
of the remnants of this band in the early Magellaniform stages, one of which is shown 
on plate XV, fig. 6. 
MAGELLANIA MACQUARIENSIS sp. nov. 
(Plate XV, figs. 13, 14, 15, 16, 17; plate XVI, fig. 40.) 
Habitat.—“On beach above present high-water level, Wireless Cove, north-west end 
of Macquarie Island, over an extent of }'mile.”—H. Hamilton. 
Some thirty specimens of this polymorphic species were obtained above the 
normal high-water on the beach of Wireless Cove, but as several of them contain the 
dried animal it is evident that they were recently cast there by a high sea, probably 
during a storm. 
There is considerable diversity in shape, between the extremes shown in plate 
XV, figs. 18 and 15, but roundly ovate shells with a broad hinge line and a 
slightly produced front predominate. The growth lines in all cases indicate develop- 
ment from a roundly ovate form, but in a few cases the adults are much longer than 
broad. The specimen chosen as holotype has the following dimensions :—Length 
26 mm., breadth 24 mm., thickness 15 mm. The shell figured in plate XV, fig. 15, 
is the only one showing a truncate front margin, which is due to a sudden reduction 
anteriorly of the broad ventral fold. The diversity in form, taken together with 
the frequency of unsymmetrical and distorted shells, may probably be correlated with 
diversity of environment such as is to be found in a shallow and stony bottom within 
range of current action.* 
The dorsal valve is only moderately convex, but the slopes leading to the umbo 
are steep. There is a median sinus which is generally rather narrow and shallow, 
giving rise to a simply curved ventral sinuation of the anterior commissure. _ In a few 
cases it is narrow, but fairly deep, and again in others it is broad and shallow, causing 
a nearly flat-bottomed ventral sinuation in the anterior commissure. The ventral 
valve is more convex than the dorsal, and presents an obscure median fold. The 
lateral commissures are straight. 
The beak is of moderate length, is sub-erect to erect, and bears fairly strong but 
blunt beak ridges. The large rounded foramen is mesothyrid in position and attrite 
in condition, but it is not completed dorsally by the deltidial plates, which are discrete 
in every case, allowing the dorsal umbo to project into the foramen. 
The test is moderately thick, and is generally in a rough condition exteriorly. 
g 
The growth lines are prominent, and there is no trace of radial ornament. The pores 
are of moderate size and number 108 to the square millimetre. 
* Distortion of brachiopods is frequently caused by the fry settling in the mouth of a boring, the diameter of which 
is too small to accommodate the adult shell, This is well exhibited in the series of Liothyrella neozelanica, described above. 
