“ TERRA NOYA ” EXPEDITION. 
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(Hector), 1887 (Withers, P.Z.S., 1913, p. 840. pi. LXXXV), differing from it. however, 
in the following particulars 
1. In the rostrum, the lateral strips marked with longitudinal lines extend to 
the base. 
2. In the laterals, the ala is relatively wider, and the internal sculpture is a little 
different, the lines of the parietal margin lacking the downward bend where they meet 
the longitudinal ridge, and the transverse lines of the ala being stronger. 
o O o o 
3. In the carino-laterals, the internal sculpture shows the same features as that of 
the laterals. 
4. In the carina, the angles of the alae are nearer the apex of the valve, and the 
transverse sculpture of the inner side is stronger and more extensive. 
The tergum and scutum are shown in Figs. 7c, The longest valve, a carina, 
would measure, if complete, nearly 90 mm. The rest are of the same order of magnitude. 
The occurrence of this barnacle presents a very puzzling problem. It is not 
possible to judge from the appearance of the shells whether they are recent or fossil. 
The valves are all disarticulated, of a pure and brilliant whiteness, and without anv 
trace of organic matter, but they are not imbedded in any matrix. They are covered 
with a very fine white dust, but this may be derived from the disintegration of their 
surface, though they are sharply sculptured, and retain Spirorhis shells that have 
grown upon them on both inner and outer surfaces. More probable traces of a matrix 
are minute sandy deposits which soil the surface here and there, but the meaning 
of these is doubtful. That the animals should be recent seems, however, hardly 
possible, for no trace of such a barnacle has been found in any dredging or collection 
either in the Ross Sea or elsewhere, nor—a stronger argument—can any satisfactory 
suggestion be made as to the way in which recent shells could have reached the position 
in which these were found. The nearest known relation of II. nntarcticum is II. 
aucldandicum from the Miocene of New Zealand. The other described members of 
the genus are recent deep-sea species of small size. Withers thinks that the loose 
articulation and relative thinness of the shell of II. aucldandicum shows that it also 
lived below the littoral zone. The shell of Id. antarcticum is similarly loosely 
articulated, though it is not particularly thin. If the new species be a fossil, it seems 
highly probable that it is. if not of Miocene age, at least Tertiary, for it is quite unlike 
any Cretaceous barnacle. Here, however, is the difficulty. No Tertiary rocks are 
known from the neighbourhood of the glacier in which the shells were found, nor, 
indeed, has anything later than the Carboniferous been reported in this region. It mav 
be that somewhere in its course the glacier is in contact with Tertiary rocks. Decision 
upon this point must rest with the geologists. It is for them also to decide what 
bearing the facts here stated may have upon the history of the Antarctic Continent.* 
* Hennig (Wiss. Ergebn. Schwed. Sudpolar-Exped. Ill, X. p. 10, pi. XI, figs. 3-7, 1911) mentions 
the existence in the Pleistocene of Cockburn Island of a small Balcmvs, but this is quite unrelated to 
Hexelasmn antarcticum. 
