164 Transactions. 
suggests agreement* with Monalaria n.g. (see. below) rather than with 
Struthiolaria. 
(b. M. minor (Marshall). The only apex seen is tectiform, consisting 
of about two smooth rounded whorls, the top one small and depressed ; 
the nucleus, however, is broken off. The first conch-whorl is convex and 
has eight spirals appearing simultaneously, but the shell is somewhat 
weathered at this point. Later the whorl becomes subangled and short, 
curved axial ribs appear on the upper part of the whorl, not reaching the 
suture below, while the spirals increase in number. T dy-whorl is 
weakly biangulate, the lower keel having two more prominent cords, the 
upper of which is moniliform. The outer lip is reflexed and thickened with 
a broad sinus above, sweeping forward to a prominent rounded wing 
opposite the lower keel, and then retreating in a shallow sinus to the 
columella. No specimen showing a complete aperture has yet been found, 
but, while the columella is twisted, it does not appear to have been bent 
inwards at the base. (See Plate 11, figs. 5, 6, 7.) 
(c.) M. concinna (Suter). The first two conch-whorls are the typical 
convex spirally-striated ones common to the apices of the family, and the 
next two show a fine development of the curved axial ribs crossed by the 
rimary spirals with secondaries appearing in the interstices; that is 
stage (b) as typified by M. minor. 
Fic. 5.—Apex of Monalaria concinna (Suter). х 3. 
On succeeding whorls the axials are much abbreviated, forming strong 
sharp tubercles on a well-developed shoulder-angle. The body-whorl has, 
in addition, a double lower keel armed with more closely set tubercles, 
while the spirals have become numerous fine regular threads. The columella 
is straight and comparatively little calloused, while the contour of the outer 
lip is exactly the same as that of 8. minor—.e., it is unisinuous. — * 
2. Genus STRUTHIOLARELLA Steinmann and Wilckens, 1908. 
Genotype: Struthiolaria ameghinoi von Ihering. 
is group was separated from Struthiolaria as a subgenus (Steinmann 
and Wilckens, 1908, p. 53) for the reception of the South American species, 
on the grounds that they differed from the typical New Zealand shells as 
follows: (1) “ Оп the older whorls spiral sculpture does not predominate, 
but axial ribs, which are, it is true, crossed by fine spirals ”: (Ge there 
is no continuous spiral angle formed on the upper part of the whorls. 
Other important features justify the separation. Ortmann’s figure of 
S. ornata (1901, pl. 33, fig. 12a), reproduced below (text-fig. 6, a), shows COP” 
vex whorls with the curved axial ribs crossed by spirals as in Monalaria, 
—— 
* A new genus seems to be required for S. lirata because of the different sculpture 
from Monalaria. 
