Boone, Mollusca, Cruises of "Ara" and "Alva" 305 



References : Patella argentata, Sowerby, G., in Captain Beechey's 

 Voy. H. M. S. "Blossom," Zool. Mollusca, 1839, p. 148, pi. 39, 

 fig. 7. 



Patella cuprea, Reeve, L., Conch. Icon., Oct., 1854, fig. 15; also 

 errata to Patella in index, Conch. Icon. 



Patella talcosa, Gould, A., in Wilkes, C, U. S. Explor. Exped., 

 Mollusca, 1852, vol. XII, p. 334, atlas XII, fig. 452. 



Helcioniscus argentata, Pilsbry, H. A., Man. Conch., 1891, vol. 

 XIII, p. 127, pi. 18, figs. 29-30, pi. 65, fig. 93. 



Superfamily: RHACHIGLOSSA 

 Family: TURBINELLIDAE 



Genus: MEGALATRACTUS Fischer 

 Megalatractus aruanus (Linne) 



i 



Plate 118 



Type: Linne confused an American and a New Guinea spe- 

 cies under his Mwrea; arwariz^. Gmelin (1788) restricted the name 

 for the New^ Guinea species. This is deposited in the "Mus. Lud. 

 Ulr. 641, No. 3221." 



Distribution : Dr. Hedley gives the Australian range of this 

 species as being from the Dampier Archipelago in the northwest 

 continuously to the Great Barrier Reef in the northeast. It is also 

 known from New Guinea and Amboina. 



Material examined: An egg-case, apparently of this species, 

 collected at Falcon Island, Palm Islands, Queensland, October 7, 

 1931. 



Remarks: The nidamental capsule, consisting of thirteen 

 parts, united at the ventral or concave side, is arranged with each 

 compartment fitting into its predecessor and receiving its suc- 

 cessor saucer-wise. The outer surface of each compartment is 

 marked by seven to nine ridge-like elevations, separated by con- 

 cave depressions, all of which radiate approximately from the 

 point of attachment, toward the margin, giving the latter a 

 coarsely crenulate aspect. The integument is a tough leathery 



