Boone, Mollusca, Cruises of "Ara" and "Alva" 299 



Discussion : The single specimen taken by the "Alva" con- 

 forms with the excellent description and anatomic figures given 

 by Bergh for his arrogans. The colour-plate given by Bergh of 

 the dorsal view has approximately only half so many fine lines 

 marking the pattern as exist in the present specimen, from which 

 the red markings are mostly faded except for a faint outline. 

 These red spots are more like those shown in the Quoy and Gaim- 

 ard plate, as are also the black lines on the ventral surface. 



So far as the present writer is aware, the "Alva" specimen 

 represents the farthest east in the Pacific that this gorgeously 

 beautiful habitant of the tropical seas is reported to date. Unfor- 

 tunately little idea of the delicate gracefulness of the living nudi- 

 branch can be portrayed. Its velvety gliding body seems a part 

 of the sea, as exquisite as a rainbow. 



References: Doris cruenta, Quoy, J. R. C, and Gaimard, J. P., 

 Voy. de L'Astrolabe, Zool., 1832, t. II, p. 260 ; atlas, pi. 18, 

 figs. 5-7. 



Platydoris arrogans, BERGH, R., Malakol. Unters. in Semper, K., 

 Reisen im Arch. Philippinen, Wiss. Resultat. II, Malakol. 

 Unters. Heft XII, 1887, pp. 513-517, taf. 51, fig. 2, taf. 59, 

 figs. 19-25, taf. 60, figs. 3-9 ; Suppl. I, 1880, pp. 58-60, taf. E, 

 fig. 39, op. cit. ; Heft XVII, 1890, p. 912, taf. 86, fig. 6, taf. 87, 

 fig. 32-33. 



Platydoris cruenta, Bergh, R., "Siboga"-Expeditie die Opistho- 

 branchiata, 1905, Leiden, Monog. L, livr. 25, p. 136, taf. 1, 

 fig. 3. 



Order: PULMONATA 



Superfamily: PTEROPHILA 



Family: SIPHONARIIDAE 



Genus: SIPHON ART A G. B. Sowerby 



Siphonaria gigas G. B. Sowerby 



Plate 115 

 Type: The type of Siphonaria gigas Sowerby was collected 

 in the Galapagos and Panama and originally deposited in the col- 

 lection of Charles Bennet, fourth Earl of Tankerville. The type 



