PLACOSTYLUS, SOLOMON IS. 85 



obliquely entering nodule near the columellar fold, and separated from 

 it by a deep and rather narrow sinus. 



Alt. 57, diam. 23, longest axis of aperture 33 mill. 



Alt. 51, diam. 21, longest axis of aperture 27 mill. 



Alt. 45, diam. 20, longest axis of aperture 26 mill. 



Wanderer's Bay, Guadelcanar 7., Solomon group (Macgillivray). 



Bidimus macgillivrayi PFR., P. Z. S., 1855, p. 108, pi. 32, f. 2; 



Monogr. iv, p. 379 CROSSE, J. de C., 1864, p. 134 Placostylus 



macgillivrayi Pfr., KOBELT, Conchyl. Cab., p. 72, pi. 17, f. 4, 5 

 (not characteristic). 



The strong development of the columellar and parietal folds, the 

 decided callous rib widening the merely expanded lip, and excavated 

 above in characteristic Placostyline manner, are the more striking 

 features of this species, the microscopic sculpture being a further 

 character of value, though shared with some other forms. The nude 

 white or pink band below the suture is occasionally indistinct 

 through partial loss of the cuticle on the rest of the shell. One 

 of the specimens before me is white under a pale yellow cuticle (fig. 

 28) and the spire is short. The aperture, however, is typically 

 developed. 



Pfeiffer's type (fig. 30) measures 59 mill, long, and is figured as 

 being more conspicuously streaked than the specimens I have seen, 

 but the figure may be exaggerated. 



Named in honor of John Macgillivray, naturalist of H. M. S. 

 "Rattlesnake," which surveyed portions of 'the Louisiades and 

 Torres Straits, 1846-1850. 



P. PALMARUM (Mousson). PI. 36, figs. 31, 32. 



Shell ri mate-perforate, ovate-oblong, somewhat solid, striate, with-, 

 a few slight spiral wrinkles ; shining, chestnut-brown. Spire high- 

 conic, regular, the apex worn, suture irregular, somewhat crenulated, 

 broadly white-margined. Whorls 4J, regularly increasing, the 

 nuclear punctate, the rest moderately convex, last whorl a little 

 ascending, as long as or longer than the spire, somewhat tapering 

 basally. 



Aperture vertical, oval, gray-brownish inside, provided with an 

 oblique, oblong, parietal tubercle ; peristome brown, thickened, 

 evenly reflexed, slightly thickened within ; the right margin arcuate 

 above, nearly straight and more thickened in the middle ; basal 



