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. The body-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 primary spirals with secondaries appearing in the interstices; that is stage (b) as typified by M. minor.

Fig. 5.—Apex of Monalaria concinna (Suter). × 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 S. minor—i.e., it is unisinuous.