R. J. L. Guppy — West Indian Tertiary/ Fossils. 435 



covered witli strong spiral ridges. Mouth subcircular. Columella 

 lip callous, produced into a broad tooth above a short broad rather 

 effuse canal. Outer lip dentate, grooved within. Total length about 

 15, greatest breadth about 12 millimetres. 



In general characters there is some resemblance between this shell 

 and Troclms cypris, Orb. (=zMonodonta elegans, Bast.). 



Trochis decipiens, PI. XVIII. Fig. 18. 



Top-shaped, imperforate, ornamented by many spiral lines of mon- 

 iliform granules; whorls rather concave above, and bearing a rather 

 broad angular keel on their lower portion ; base flattened, covered 

 with lines of rather square granules, aperture subquadrate, wider 

 than high, broadly angulate by the keel ; columella thickened, spread- 

 ing into a callus over the umbilicus. ^ 



Var. laticarinatus, PI. XVIII. Fig. 19. 



Keel broader and higher, whorls deeply concave above, suture 

 deeply impressed ; lines on the base squamosely granular. 

 Pliocene, Trinidad. 



TrocJius pUcompJialiis, PL XVIII. Fig. 17. 



Top-shaped, deeply perforated by a small circular umbilicus, zoned 

 with many spiral granular lines, aperture subquadrate, columella 

 straight, thickened ; base with many (10-20) moniliform rows of 

 granules, umbilicus deep, its margins dentate. 



Pliocene, Trinidad. It resembles T. zizipMnus in shape, but is 

 devoid of any keel on the whorls. 



Vitrinella marginata, PI. XVIII. Fig. 21. 



Orbicular, umbilicate, discoidal, few-whorled, minutely spirally 

 striate ; outer margin with about four small articulated keels not 

 visible from above, the outer one forming the periphery ; whorls 

 somewhat convex above ; spire raised, ornamented with articulated 

 radiating striae ; aperture nearly circular, rather oblique. 



Pliocene, Trinidad. A most elegant little shell. 



Crucihulum piliferum. 



Shell covered with numerous erect tabular spines which are small 

 towards the apex, larger towards the base ; apex small, smooth, 

 spirally recurved. 



Pliocene, Trinidad. It may be a variety of the next species, but 

 its plic^ are smaller, whilst the spines furnish an easily-recognized 

 character. 



Crucihulum subsutum, PI. XVIII. Fig. 4. 



Strongly striate, rugose, somewhat irregularly oval; striations 

 with a tendency to run in pairs. 

 Pliocene, Trinidad. 



Donax fahagelloides, PL XVIII. Fig. 10. 



Transversely oblong, somewhat triangular, subequilateral, anterior 



