300 MARGARITA. 



This shell slightly recalls Helix ericetoruni, Miill. but much niore- 

 closely resembles some of the West Indian land-opercvilates, such 

 as Aulopoma. With its semi-continuous peristome it very much re- 

 calls a Cyclostrema, all the more so that it is less pearly within, less 

 nacreous and more chalky, and less globosely conoidal than Margaritas 

 usually are ; but I have no doubt that it is a Margarita. Trochus 

 (Margarita) umbilicalis, Brod. and Sow , is vaguely like, but is very 

 obviously different ; the apex is not so exserted as here, the whorls 

 are of much more rapid increase, and form a much larger though 

 lower spire; the last whorl is proportionally much more tumid and 

 above is more flattened, the suture is much more oblique, the um- 

 bilicus is very much smaller and more covered by the inner lip, and 

 the hard, polished, buff-colored porcelanous outer layer of the shell 

 (which is very like that in Trochus (Margarita) expansus. Sow.) is 

 very unlike. ( Watson.) 



About 900 miles S. E. of Kergaelen, 1260 fms. 



T. (Margaritci) brychius Watson, Journ. Linn. Soc. Lond. xiv, 

 p. 699 ; Challenger Gasterop., p. 77, t. 5, f. 7. 



M. charopus Watson. PI. 64, figs. 55, 56. 



Shell globosely conical, like a Cyclophorus, thin, translucent, 

 umbilicated, iridescent, banded. Sculpture: Of spiral threads there 

 are from twenty-five to thirty-five, sharply projecting, rounded, and 

 fine on the last whorl ; of these, from three to seven are feebler 

 than the rest; those on the base are continued within the mouth. 

 The interstices are much broader than the threads. The whole sur- 

 face is also fretted by microscopic spirals and stronger longitudinals, 

 which follow the oblique lines of growth. Of the threads, six to 

 thirteen appear on the penultimate whorl ; they begin with the 

 second whorl, and there the longitudinals are rather dispropor- 

 tionately strong and regular. The embryonic apex is faintly but 

 coarsely tubercled. Color yellowish white, shot on the upper side 

 with a dark iridescence ; the spirals are black, clouded, and broken 

 with oblique longitudinal streaks of white. The spire is high and 

 scalar. The apex, porcelanous and scarcely iridescent, is small, 

 high, and mammillate, and consists of the one embryonic whorl, 

 which is a little turned up on its side. Whorls 6, of gradual and 

 regular increase, rounded, near the apex a little angulated by one 



