PARTULINA, MAUI. 69 



Partulina mutabilis BALDWIN, Nautilus, xxii, p. 68, No- 

 vember, 1908. 



Distinct by its narrow contour, color in bands when pres- 

 ent, and the frequent presence of a brief zebra-striped stage on 

 the last embryonic whorl. It has a superficial resemblance 

 to the Lanaian A. variabilis, which belongs however to a 

 somewhat different series, Figured from specimens of the 

 type lot received from Mr. Baldwin. 



P. mutabilis is an important species in that it forms a con>- 

 nection between the Partulinae having zebra striping and 

 those having spiral bands only. The embryonic whorls are 

 flattened, the first flesh-tinted. In most banded individuals 

 some indistinct protractive brown streaks appear near the 

 end of the second whorl, becoming stronger and angularly 

 bent on the next fourth to half whorl, gradually giving place 

 to spiral bands which arise about the middle of the third 

 whorl (pi. 20, figs. 6, 7). This pattern is not essentially un- 

 like that of Partulina splendida. In some individuals, how- 

 ever, the longitudinally striped stage is omitted, and the spiral 

 bands appear (at first very faintly) on the latter part of the 

 second whorl, arising from the uniform fleshy tint of the pre- 

 ceding part of the embryonic shell (pi. 20, fig. 5). Such 

 shells are comparable to P. porcellana and its allies, and may 

 be regarded as more accelerated than those having an ob- 

 liquely striped stage. 



In a series of 18 sent by Mr. Baldwin, 10 are dextral. The 

 same color patterns are found in dextral and sinistral indi- 

 viduals. The variations are as follows: 



(1) Pure white throughout. 



(2) Pale buff, last embryonic whorl faintly striped longi- 

 tudinally. 



(3) White to buff-yellow with chestnut bands and lines. 



38. P. PORCELLANA (Newcomb) . PI. 19, figs. 1 to 4. 



11 Shell rather solid, conical, polished, shining. Whorls 

 5, rounded, margined above. Aperture ovate; lip expanded, 

 thin at the margin, thickened within. Columella short, tuber- 

 cular. Color of a porcelain whiteness with a light fawn- 



