THE NAUTILUS. 99 



figures 11 and 12, an albinic form. Nobiiis represents the large 

 three-banded form, pica the brown form with large white sub- 

 triangular spots, and tenebrosa the almost or entirely brown form. 

 Length 70-100 mm. 



The thick, light-colored var. ponderosa is intermediate between 

 forms referable to tremulina on the one hand and miniacea on 

 the other. The latter both Bolten and Lamarck refer to the 

 same figures by Martini (Conch. Cab., ii, tab. 45, figs. 476, 

 477). I have restricted the porphyritica to the small form (45- 

 55 mm. ) with bands of bright purple spots, of which I have 

 recently received specimens through Mr. Wm. N. Southern, 

 collected by Mr. Frank E. Rand, at Ponape, Caroline Islands. 

 The name of sylvia is applied to the orange-yellow form with a 

 red aperture, and marrati to the dark brown red-mouthed form 

 as figured by Marrat, (Thes. Conch., pi. 7, f. 109), represent- 

 ing a parallel variation to that of tenebrosa and fordi. 



The subspecies irisans, though poorly defined, is the oldest 

 name and has already been applied to various forms of this 

 group by authors. There is only one figure referred to by 

 Lamarck that can be considered as irisans (Martini, Conch. Cab. 

 II, Tab. 561); the others are questioned. This figure has not a 

 callous spire and the description " spire acuminate" does not 

 apply to the low callous-spired forms, figured by WeinkaufT, 

 Marrat and Duclos, but to the form figured by Reeve (PL 6, 

 fig. 8b). Figure 8d is the orange-yellow acutely spired zeilanica 

 and fig. Sa the low callous-spired ornata. The typical cryptospira 

 is light yellow with only slight traces of dark marking (Thes. 

 Conch., pi. 9, f. 125) while furdi is the dark brown, callous- 

 spired form (Thes. Conch., pi. 9, f. 126). There is also a pure 

 white, callous-spired form (albescens}. 



2. OLIVA OLIVA (Linne). 



Valuta oliva Linne", Syst. Nat., 10 ed. p. 729, 1758. 

 Porphyria vidua Bolten, Mus. Bolt., p. 35, 1798. 

 CylindrusnigellusM.eu.scla.Qn, Mus. Gevers. , p. 376. 

 0. maura Lam., Ann. du Mus., xvi, p. 309, 1810. 

 0. mauritiana (Martini) Marrat (pars) Thes. Conch., iv, 

 pi. 10, 1870. 



