MOLLUSCA OF THE ' OHALLENOEU ' EXPEDITION. 701 



but not sliarply so. MoutJi rather oblique, round, hardly angu- 

 lated at the upper corner, not in the least descending, brilliantly 

 iridescent within and showing the coloured spirals of the outside. 

 Outer lip thin, slightly puckered at the spirals, a little thickened 

 on the base. Inner lip thickened and reflected, especially at its 

 junction with the body, where it almost covers the umbilicus. The 

 pillar is much curved, and thins gradually out to -its junction 

 with the base. The umbilicus is large and funnel-shaped on the 

 base, deep, but small further in, contracted by a spiral white 

 pillar-pad, and more than half covered over by the pillar-lip. 

 Operculum rather thin, horny, yellow, with ten to twelve very 

 gradual turns, which are strongly defined by a thickened line ; it is 

 feebly marked with concentric and with radiating lines. H. 0-77. 

 B. oVs, least 0'66. Penultimate whorl 0-2. Mouth, height 0-4, 

 breadth 04. 



There is a M. striata, Leach (nee Brod.), which this resembles, 

 but is very much more flattened and broader, and much more 

 contracted in the spire. 



Yar. ciEEULEUs, W. 



St. 151. Feb. 7, 1874. Heard Island. 75 fms. Mud. 1 spe- 

 cimen. 



This difi'ers from the type in having only four spiral threads 

 above the periphery, while on the base below the peripheral 

 thread the threads are also fewer, and are flattened out till they 

 are barely parted by narrow lines of iridescent white. "With 

 the exception of these and the white umbilicus, the base is 

 of an intense blue-black grey. The comparative absence of the 

 spirals on the upper part of the whorls gives a flatness to the 

 aspect of the shell below the suture, while the strength of the 

 second and fourth spirals gives an angulation to the whorls that 

 is apt to mislead the eye, the more so that the only specimen 

 of this variety has the whole spire completely covered with 

 Polyzoa. In spite, however, of its decejptive appearance, 

 I am persuaded that this is only a variety of T. cliarofus, 

 the more so that the markings on the embryonic whorl are 

 identical. 



In form this variety especially recalls Margarita polaris, Beck 

 (Greneva Mus., Coll. Delessert), as also in its distant rather sharp 

 spirals and half-covered umbilicus, but is more depressed on the 

 base and flattened below the suture ; the whorls are of much 



