26 AUSTRALASIAN ANTARCTIC EXPEDITION. 
Type.—A female, Cat. No. C. 40892, of the Australian Museum [S.S.B. 440]. 
Type Locality.—Station X., Lat. South 65° 6’, Long. Hast 96° 13’, off the Shackleton 
Ice-shelf, Queen Mary Land; 325 fathoms, ooze; bottom temp. —1-65 C.; January 
29th, 1914; one 9? specimen. 
Material Examined : 
Spot Sex. | Depth. Locality. ieee a. Ces Date. Bee Remarks, 
2 wae Binet 
1 2 270 | Off Shackleton Ice-shelf . Trap C. T. Harrisson .. | Jan,, 1913... [441] — 
1 2 | 325 io “h Trawl Station X. .. sees Jan, 29, 1914 [440] Type 
1 2 358 a tt Le st Station XI. ..... Jan, 31, 1914 [442] Paratype 
1 —t 358 ay Se Bs H- Station XI, ..... Jan, 31, 1914 [443] _ 
Remarks.—This species is represented in the collection by more material than any 
of the others collected, a fortunate circumstance, since the specimens serve to verify 
many of the characters which have been held to be of taxonomic significance. Although 
the above description has been drawn practically in its entirety from the type, as the 
better preserved of the two largest specimens, both paratypes check up well with it, and 
on the whole give evidence of remarkably little variation. 
Fig. 24.—M. harrissoni. 
Radula. 
Owing to its similar color and consistency, and the short umbrella, M. harrissoni 
at first sight reminds one very much of the M. adelieana already described, but the duplex 
funnel organ (probably derived, however, from an organ shaped much like that of 
M. adelieana), obscurely papillose surface, conspicuous subperipheral fold, and notable 
differences in the radula are amply sufficient to distinguish them. The taxonomic 
value of the peripheral fold has been called in question by several writers, but, so far 
as my experience goes, its presence or absence in well preserved material is a matter of 
great constancy, and this is true of even very young specimens. 
The juvenal taken at Station XI. agrees with the larger specimens in its short arms, 
short umbrella, and wide body, as well as the peripheral fold. The small papille, 
