164 



Bulletin 39 



33^ 



Genus CALLfOSTOMA Swainson 

 Calliostoma Simonensis, n. sp, Plate 15, figures 8, 11 



Shell of medium size, conic; whorls about 8, flat or but 

 slightly convex, so that the profile of the shell is a broad cone; 

 sutures indistinct; the whorls are closely sculptured with fine, 

 beaded spirals of primary and secondar}^ orders; each spire-whorl 

 has 7 or 8 primary spirals alternating with i, 2 or 3 secondary; 

 peripher}^ sub-angular; base but slightly convex and closely spir- 

 alled with fiat or sub-obsoletely beaded spirals (about 20), umbil- 

 icus narrow but deep, smooth within. 

 Height 19, diameter 18.5 mm. 



Fairly abundant in the coral limestones along the shore west 

 of Port Limon. Related to the recent C. jujubinum Gmelin, it 

 differs by its more globose form and small, pointed attenuated 

 apex. 



Gabb has also described a small Callio stoma from the Linion 

 Peninsular, as C. Guppyana. This shell of 8 or 9 whorls meas- 

 ures but 5 mm in height. It is a higher and more conic form 

 with the whorls sculptured with beaded spirals. 



Gatu7i Stage: Port Limo7i. 



Calliostoma mancinella, n. sp. Plate 15, figures 9, 10 



Shell of medium size; whorls about 8, with very indistinct 

 sutures and a coarse sculpture of beaded spirals; the spire whorls 

 are flat sloping evenly from the small projecting nucleus to the 

 broadly rounded periphery of the last whorl; sculpture of the 

 spire-whorls consists of about 6, strongly beaded spirals the 

 largest of which bounds the upper sutures; between these spirals 

 are scattered a few smaller ones, the lower half of the peri- 

 phery and the base have about 12 additional spirals; these 

 spirals are larger, more widely spaced and are smooth except 

 the 4 or 5 around the umbilicus; the interspaces of the basal 

 spirals are finely incised by minute longitudinal lines, corres- 

 ponding to the growth lines; umbilicus narrow, but deep, 



