Narrative of the surveying voyages of his majesty's ships Adventure and Beagle (vol.1): between the years 1826 and 1836 : describing their examination of the southern shores of South America, and the Beagles's circumnavigation of the globe

CATALOGUE^ — SHELLS. ' 557 labri margine tenui, castaneo-maculatd ; long. ^3 ; lat. ^i ; poll. Habitat ? Mus. nost. 51. LiTTORINA STRIATA. L. testa ovato-coniccifjuscd, striis elevatis scahrd ; spird brevi ; an- Jradu basalt tumido ; aperturu nigricante, basin versus strigd luleo- albd ornatd; labri margine crenulato albo-fulvido ; operculo nigro ; long. I 'paulo plus ; lat. -^^^Jere ; poll. Habitat in Mari Atlantico boreali (Port Praya). Mus. Brit., nost. 52. Margarita fasciata, n. s. M. testd albidd, creherrhne striata, purpureo Jasciatd, aperturd ar- gcnted J long, -f^^ ; lat. -fgjere ; poll. Habitat in Mari Pacijico. Mus. nost. Portions of the striated surface are elevated into belts, which are of a purple colour. 53. Margarita violacea. M. testd sub-ovatd, violaced, spird brevi; anjractibus tumidis aperturd iridescente ; long. -^^ ; lat. -i^fere ; poll. Habitat ad Jretum Magellanicum. Mus. Brit., nost., Brod. Of this shell the Indians make their necklaces ; it is found adher- ing to the leaves of the Fucus giganteus, and is the principal food of the Steamer or Racehorse Duck (Micropterus Patachoni- cus, nob. in Proceedings of the Zoological Society, December 14<, 1830, page 15). 54. Margarita ccerulescens. M. testd sub-complanatd, cceruled, striata, albido-lineatd, aperturu iridescente; lat.\^Jere; long.^^; poll. Habitat ad Jretum Magellanicum (Cape Gregory). Mus. Brit., nost., Brod. 55. TURRITELLA TRICARINATA. T. testd turritd, anjractibus tricarinatis ; carinis nodulosis ; long. 1| j lat. -9g paulo minus ; poll. Habitat ad oras AmericcB meridionalis (Valparaiso). Mus. Brit., nost., Brod. The Carince are nodulous, or twisted like the strands of a rope ; the twists of the upper carina are in the direction of a water-laid,