HENSHAW : SEMI-FOSSIL SHELLS IN HA.MAKUA DISERICT, HAWAII. 6l 



species but exhibiting greater or less differences. Living species of this 

 group are difficult enough of determination, even with the aid of abundant 

 material and field notes. How much greater the chances of error with only 

 fossil material available I The author has intended to be extremely con- 

 servative in describing forms, preferring to leave a few for future describers 

 rather than to add to the number of synonyms, already too many, in this group. 



Sueeinea maxima, n. sp. 



PI. V, figs. I, 2. 



Shell elongate, narrow, rather thick, lines of growth fairly distinct. Spire 

 very small, considerably less than -^ the whole length of shell, conical, slightly 

 produced, apex mammilliform, suture moderate. Whorls, 3 ; ultimate whorl 

 very large. Aperture large, but slightly oblique, ovate, reduced above. 

 Columella but slightly curved. Peristome simple, acute. 



Long. 24, lat. 1 1.5 millim. : long, apert. 16 millim. 



Hah. — Mana, Hamakua, Hawaii. 



This species is without doubt the largest of the genus yet discovered in 

 the Hawaiian Islands, and differs also otherwise from described forms. The 

 axis of the shell is nearly medial, the apex forming but a very slight angle 

 with the body of the shell. The apex is very small in comparison with the 

 lest whorl, averaging less than one-third the length of the latter. A single 

 specimen of this species was found in the Palihoukapapa deposits, but the 

 species abounds in those at Mana. 



Sueeinea mirabilis, n. sp. 



PI. V, figs. 3, 4. 



Shell moderately thick and firm, acutely cone-shaped with very obliquely 

 truncated base ; lines of growth distinctly marked ; spire relatively large, 

 autish, mammilliform, composed of two convex whorls with well-defined 

 sutures ; aperture rather narrowly ovate, rather less than two-thirds the length 

 of the shell ; columella decidedly curved and slightly reflexed ; peristome 

 simple, acute. 



Long. 16, lat. 8 millim. ; long, apert. 11 millim. 



Hah. — Palihoukapapa, Hamakua, Hawaii. 



As regards its shape, this shell is far the most remarkable of Hawaiian 

 Succineas, living or extinct. The lower whorl spreads widely, and the aper- 

 ture is so oblique to the axis that, when the shell is placed on its base, the 

 apex makes a very acute angle. The apex is also very large as compared 

 with the lower whorl, being contained in the latter only twice. The species 

 appears to be only moderately abundant in the deposits. 



This species bears a very remarkable resemblance to the S. infuii- 

 dihidifonnis, Gould, fiom Tahiti. 



