30 PROCEEDINGS OF THE NATIONAL MUSEUM yoL. 06 



lip broken away ; pillar with two oblique, rounded threads ; anterior 

 canal short, partly broken away. 



Dimensions: Type (U. S. Xat. Mus. Cat. No. 352025) measures: 

 Altitude 3.6 mm. ; greatest diameter 1.5 mm. 



The new species is very similar to Microdrillia tHna but is much 

 stouter than that species and possesses a much shorter nucleus. 



Occurrence. — Middle or lower Miocene : In flood-wash, 1 mile south 

 of Brasso railway station. Trinidad, British West Indies. 



Genus BORSONIA Bellardi 



Subgenus Paraborsonia Pilsbry 



BORSONIA (PARABORSONIA) BRASSOENSIS. new species 



Plate 5, fig. 8 



Borsotiia raricosa Maury (not of Sowerby), Bull. Amer. Paleont., vol. 10, no. 

 42, p. 192, pi. 34, fig. 7, 1925. 



Shell of medium size, biconic. solid, elaborately sculptured, seven 

 and one-half whorled including one and one-half nuclear whorls. 

 Nucleus smooth and globular. Postnuclear spire w^horls gradually en- 

 larging, in outline nearly straight, and only slightly constricted at 

 the shallowly grooved suture. Sculpture consists of three primary 

 spiral bands, finely tuberculate on the earlier whorls, coarsely elon- 

 gate-tuberculate on the later whorls ; the posterior band is widest and 

 nearlv marginates the suture except for two spiral threads just an- 

 terior to the suture, and separated in front by a rather wide chamael 

 in w^iich are irregular axial gi-owth lines; the two anterior bands are 

 narrow, closely spaced, axially crossed and connected by elongate 

 tubercles or short ribs and occupy the low periphery of the whorl ; one 

 or tw^o granulose spiral threads are between the peripheral bands and 

 the forward suture. Sculpture of the body whorl, below the periph- 

 eral bands and extending to the end of the canal, consists of about 

 thirteen narrow, semituberculate, wide-spaced, spiral bands interca- 

 lated by a varying number of fine, spiral threads. Margin of outer 

 lip broken. Urate within; columella with three plications — the pos- 

 terior one is strong, the anterior one weak. 



Dimensions: Type (U. S. Nat. Mus. Cat. No. 3526G1) measures: 

 Altitude 14.3 mm. (end of canal slightly broken away) ; greatest 

 diameter 6.5 mm. 



The new species closely resembles Borsonia {Parahorsonia) var'i- 

 cosa (Sowerby). Sowerby 's species, however, possesses a higher 

 peripheral bilirate band, and a lower and more granulose siibsutural 

 band. 



Occurrence. — Middle or lower Miocene: In flood-wash, 1 mile 

 south of Brasso, Trinidad. 



