ANTILLEAN OBELISCUS. 269 



the islands mentioned above except Guadeloupe. It is dis- 

 tinguished by the wholly imperforate axis at all stages of 

 growth, the <eolumellar margin being very narrowly renexed 

 and closely appressed, leaving no trace of an umbilical slit. 

 The columella is rounded and somewhat thick above, but 

 tapers downwards, not reaching to the base, which recedes 

 somewhat. Specimens from St. Thomas (pi. 30, figs. 1, 2) 

 are usually not very glossy, adults measuring : 



Length 8, diam. 2, aperture 2 mm., with 8 whorls. 



Length 7.5, diam. 2, aperture 2 mm., with 7y 2 whorls. 



Some of the original lot in the Swift collection are before 

 me. As the above measurements show, the contour varies 

 from a wider to a narrower phase. 



Porto Rican shells are more glossy and translucent, with 

 Whitish suture 'and the whorls seem a little more convex. 

 Those from Cuba, pi. 30, fig. 4, received from Arango as 8. 

 cjutierrezi, are similar but a little more robust; one of the 

 wider phase is illustrated, length 8, diam. 2.25 mm., whorls 

 7y 2 . In Bermuda the shells are finely developed, length 10, 

 diam. 2.3, aperture 2.1 mm., with as many as 9 whorls (pi. 

 30, fig. 3). 



In the structure of the columella, this species is like Obe- 

 liscus rather than Opeas; but some approximation to the same 

 form is found in 0. octogyrum, a species with more flattened 

 whorls and a larger embryonic shell. None of the specimens 

 seen contain eggs, such as are commonly seen in Opeas. It is 

 probably viviparous, like all Obelisci. 



In Havana, Bermuda and Mauritius this species is appar- 

 ently an immigrant, introduced by commerce, probably from 

 Porto Rico. 



27. 0. SALLEANUS (Eeeve) . PI. 40, figs. 1, 2, 3. 



Shell imperforate, solid and strong, turrite, white under a 

 yellow cuticle which is obliquely and indistinctly streaked 

 with brown, and when unworn is very shortly and densely 

 lamellose on the last whorl. Surface not glossy, finely sub- 

 striate, and subob'soletely but closely spirally striate, the 

 spirals most prominent in unworn shells, being chiefly cutic- 



