106 MONODONTA. 



triangulate ; columella oblique, suhtruncate and binodulose at base ; 

 lip acute, wide, with a porcellanous greenish margin, edged with 

 black, inside of which it is silvery, pearly, throat porcellanous, 

 subsulcate. (Phil.) 



The shell is rather thick ; the whorls are slightly convex, the 

 upi^erones eroded, grayish-white, the last impressed at the suture, 

 rounded beneath. The columella is round, oblique, and makes a 

 distinct angle with the preceding whorl ; below it is truncated, and 

 has two little tubercles ; the upper angle of the aperture is rounded,, 

 not channeled, even if distinctly angular. The place of the inner 

 lip is absorbed, smoothed (forming a negative inner lip). In the 

 umbilical region there is a porcellanous, slightly callous deposit. 

 Alt. 34, dlam. 31 mill. (PhilippL) 



King George's Sound, S. Australicu 



Can this T. carbonarius be only an adult specimen of T. diloma 

 Menke? The latter is distinguished by (1) its smaller size, (2) the 

 entirely black margin of the outer Yip, (3) a distinct furrow at the 

 upper angle of the aperture, (4) the much less conspicuous angle the 

 columella makes with the upper whorl, (5) in lacking truncation and 

 denticles at the base of the columella. (Pltilippi.) 



T. carbonarius Phil. Zeitschr.f. Mai, 1848, p. 105 ; Conchyl. Cab.y 

 p. 276, t. 40, f. 9. 



Known to me only by the above description and figure. (Compare 

 Chlorostoma fiinebrale.) 



M. NERiTOiDES Philippi. PI. 34, figs. 20-22. 



Shell semiglobose, very oblique, im})erforate, smooth, black, painted 

 with numerous white zigzag lines; whorls rapidly widening; spire 

 retuse ; aperture semiovate; lip thin, duplicated and coarsely crenate; 

 columella tlat, grooved by a parallel sulcus, terminating in an acute 

 tooth below. (Phil.) 



The shell is ver}'^ similar to a Nerita on account of its semiglobose 

 form, very obtuse spire, flat base and rapidly widening w^horls. I 

 count 5 volutions ; the uppermost are flat, and spirally striate ; the 

 penultimate convex, the last completely smooth, obliquely descending, 

 flatly depressed above, almost concave. The aperture is almost 

 exactly like that of T. canaliferus. The outer lip is on its outer part, 

 inside the edge lined with mother-of-])earl, visibly farrow^ed ; on this 

 part borders a white porcellanous coat, underneath standing out like 

 a rib, on the base cut by two furrows ; the throat is nacreous all 

 around. The columella is compressed, flat, arcuate, produced into a 



