OF SANTO DOMIXCO. 



241 



T have specimens which correspond with tlie description, though not with the 

 figure of Yermetus papulosiis, Guppy, loc. cit., Vol. XXII., p. 292, ph 17, fig. 6. The 

 ilhistration does not show the tubercles arranged "in regular longitudinal rows" nor 

 does it exhibit the striae. My specimens do, however, and I believe them to be the 

 large terminal end of the tulies of P. sculpturatus. 



The internal plates of Petaloconclius arc by no means constant in either the 

 straight or the spiral portions of the shell. In fact I find them to occur rather in a 

 minority of my specimens. May they not have rather a eexual value? The genus 

 can always be distinguished from Vermetus by the irregularity of its spiral. In the 

 latter genus, the spire is as regular as that of Turritella ; in the present one it is 

 never uniform. 



CAECUM. Flem. 



C. an nil latum. Gabb, n. s. 



Shell minute, arcuated, rather thick, covered by transverse ribs, becoming finer and more closely iilaced near the 

 aperture. In the interspaces between the ribs are minute longitudinal lines. 



More robust and less arcuated than C. trachea, and differs from it in the details of 

 sculpture. 



C. c o n s t r i c t u m . Gabb, n. s. 



Shell minute, slightly curved, tapering slightly toward the truncated ajiex ; septum prominently convex ; aperture 

 distinctly narrowed. Surface smooth. 



With the smooth surfiice of C. glahrum, this little shell differs in the constricted 

 aperture. - , 



ONUSTUS. Humph. • 



O. i m p e r f o r a t II s . Gabb, n. s. 



Shell broad, trochiform, moderately elevated, whorls seven, convex above, margins squamose, suture minute, 

 not undulated ; upper surface covered by fine oblique irregular lines, sometimes dicliotomous ; under surface 

 marked only by lines of growth. Umbilicus small, almost entirely covei-ed by an expansion of the inner lip, its 

 margin regularly rounded. Aperture sub-elliptical, outer edge acu.te. 



About the size of 0. exustus, but differs in its mai'kedly smaller umbilicus with 

 rounded margins, and in the non-stellate character of the squamose plate. 



PHORUS. Montf. 



P. agglutinans. Lam., sp. 



P. onusiiis, live. Icon. Conch., No. 3. 



Troclius agglutinans, Lam. 



Seventeen specimens were found, and on the lai'gcst, which is nearly naked, are 

 several fragments of Petaloconclius. 



CRUOIBULUM. Schum. 



C. spinosirm. Sby., sp. 



Calyptrwa spinosa. Sby., Gen. of shells, sp. C. 



Crucibulum spinosum. live.. Icon. sj). 10. 



Very rare, but shows several varieties, as is usual elsewhere. I have it spinous, 

 striate, smooth; very high, nearly flat ; thin and tliick, round, oval, and irregular. 



A. P. S. — VOTi. XV. 3l. 



