no. 2091. REDISCOVERY OF POURT 'ALES' HALIOTIS— HENDERSON. 661 

 HALIOTIS (PADOLLUS) DALLI, new name. 



Plates 45 and 46, lower figures. 



1889. HaUotis pourtalesii? Dall, Proc. U. S. Nat. Mus., vol. 12, p. 355, pi. 12, 

 figs. 1,3. 



1890. HaUotis pourtalesii Pelsbry, Man. Conch., ser. 1, vol. 12, p. 121, pi. 22, 

 figs. 27, 28. 



1893. HaUotis pourtalesii? Stearns, Proc. U. S. Nat. Mus., No. 942, vol. 16, 

 pp. 418, 448. 



The following is Doctor DalTs description in full: 



Shell small, of a pale brick-red color, with white dots on some of the spirals, rather 

 elevated, with about 2\ whorls; apex small, prominent; holes about 25, of which 5 

 remain open, the margins of these rather prominent; outside the row of holes the 

 usual sulcus is strongly marked; about midway from the suture to the lines of holes 

 is a raised rib, rather obscure but differing in different individuals and corresponding 

 to an internal sulcus; between the central ridge and the suture there are no undulations 

 or transverse ridges of consequence; sculpture of well marked, rather flattish, spiral, 

 close-set threads, sometimes with a single finer intercalary thread, overlaid by smaller 

 rather compressed transverse ridges, in harmony with the incremental lines; on top 

 of the spirals the ridges bulge like the threads of worsted on canvas embroidery; spire 

 situated well forward and with sub-vertical sides; interior pearly, the coil of the spire 

 rather close and the margin of the pillar flattened. Longitude of shell, 23; latitude, 

 18; altitude, 11.5; nucleus behind the anterior end, 17 mm. 



Hah. — Station 2815, in 33 fathoms, sand; near Charles Island, of the Galapagos 

 group, in the Pacific. 



The nearest relative of this shell is H. parva, from the Cape of Good Hope, which 

 differs from our specimens chiefly in the greater prominence of the central rib, and 

 in being a little more circular in outline. 



The shell from the Galapagos agrees so exactly with what we know of H. pourtalesii 

 and with my own recollection of the type specimen destroyed in the Chicago fire, 

 that I am unwilling to separate it, though the distance between the two localities 

 is so great. 



The occurrence of this shell at the Galapagos is of great interest apart from its 

 supposed connection with the Floridian species. No species of HaUotis is known 

 from the west coast of South America, of Central America, or of North America south 

 of northern Mexico. There are one or two small not nearly related species in the 

 Melanesian Islands and north Australia. So the present species is remarkably 

 isolated. Nothing of the sort has been previously reported from the Galapagos. 

 Two specimens were obtained, neither containing the soft parts. The original type 

 of H. pourtalesii contained the animal. It would probably be referred to the section 

 Padollus. 



