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Show 380 MR. R. B. WATSON ON MADEIRAN MOLLUSKS. [Mar. 18, that occupied by the lines. Sometimes these longitudinal lines are interrupted, and a sudden return is made to the spiral-dot arrangement ; sometimes, after one, two, or three spiral lines of dots, the longitudinally confluent lines are reverted to. On the base there is much less tendency to this longitudinal confluence of the dots. Round the pillar they are entirely absent; and this part has always some tendency to be milky white. On the first two whorls these dots are also absent, but two or three series appear on third whorl. In some cases these dots remain projecting when the rest of the surface has weathered off. Besides these crimson dots, and quite independent of tbem, there appears at the periphery of each whorl a single series of much larger (g-0 ^-inch square), opaque (not opalescent nor transparent) white spots (whence the name). They are oval or circular, not irregular or indefinite in outline ; ten or twelve go to each whorl. Their lower edge is exactly cut off by the spiral furrow. In the fourth and fifth whorls they lie quite above the suture. They seem much less superficial than the crimson dots ; but it is they which efface those when they interfere with one another. When tbe shell is no longer fresh, the crimson of the dots fades to a ruddy brown, and the glassy transparence of the shell becomes troubled; but some trace of the white spots can generally be discovered to the last. The tip of the shell is opaque white, with no trace of brown stain on embryonic whorl. Spire elongated, regularly contracted, ending in a blunt, round, and slightly depressed apex. Whorls 5|, a little angularly rounded ; the spiral furrow on base produces a very slight carination just below periphery. Suture straight, broad, and shallow. Mouth small, irregularly quadrangular, caused by the great length and extreme straightness of the pillar, by the angularity of its junction with the body and still more with the outer lip, by the great straightness of the outer lip and its tendency to a slight angulation at its outer and lower corner, and, finally, by the flatness of the basal line. In the young shell these characteristics, though traceable, are not so strongly pronounced as in the old. Outer lip sharp, thin, straightish, contracted rather than expanded, at lower corner a little more extended and opener, across base flattened and slightly patulous, joining pillar at a distinct angle. Inner lip straight, sharp-edged, slightly bevelled back rather than reflected on the long and straight pillar, where it forms a slight and very shallow umbilical chink; it leaves the pillar a little angularly, and is continued across belly to join outer lip, which it reaches at almost a right angle. Sh. M. 6. 5. 4. 3. 2. 1. L *09 *036 *037 *022 *014 *009 *005 *003 B *05 *031 *032 *047 *035 *022 *014 *007 Hab. Gorgulho, shore; mouth of Ribeiro Secco, Funchal, 10 fathoms; Santa Cruz, 10-15 fathoms; Machico, 10-15 fathoms; Piedade (Canigal), 15-35 fathoms ; Ponta de S. Lourengo, 25-45 |
