THE CYCLOPHORI'D LAJnTD MOLLUSKS OF AMERICA 121 



inflated, strongly rounded, and marked by rather coarse axial riblets. 

 In addition to this, beginning with the second whorl, rugations make 

 their appearance, which gradually increase in size. These ridges are 

 less pronounced on the summit and grow stronger toward the periph- 

 ery. They have a zigzag protractive slant. Suture well impressed, a 

 little less so on the last turn, which is appressed to the preceding 

 whorl. Periphery well rounded, marked by the feeble continuation 

 of the axial sculpture. Base strongly inflated, strongly rounded, 

 with a strong keel marking the outer edge of the moderately large 

 umbilicus. The inner edge of this keel is decidedly inpinched, while 

 the outer is bounded by a series of deep pits which give the shell 

 the appearance of having been bitten by pointed teeth, hence the 

 name. The spaces between these pits form cords which are poorly 

 developed, short, and protractively bent. These cords disappear on 

 the last portion of the last turn. The posterior portion of the base 

 is without nodules. The umbilical wall is marked by rather pro- 

 nounced axial riblets. Aperture subcircular, decidedly oblique, pro- 

 tracted into an angle at the posterior angle ; the outer lip of the peri- 

 stome is thin, the inner somewhat thickened. Operculum typically 

 cyclobakerid. 



The specimen figured, U.S.N.M. No. 401305, is one of a very large 

 series collected by C. R. Orcutt 21/2 miles east of Bath, St. Thomas 

 Parish, Jamaica. It has 4.9 whorls and measures : Height, 16.2 mm. ; 

 greater diameter, 25.0 mm. ; lesser diameter, 17.9 mm. 



The species appears to extend over the entire southeastern portion 

 of St. Thomas Parish. 



POTERIA (CYCLOBAKERIA) CHITTYI, new species 

 Plate 17, Figubes 4r-6 



Shell small, helicoid, chestnut-brown; nuclear whorls paler. The 

 nucleus consists of a single well-rounded, smooth turn. The post- 

 nuclear whorls are inflated, strongly rounded, and marked by hair- 

 like, retractively slanting axial riblets, which increase in strength as 

 the shell progresses in growth. Beginning with the third postnu- 

 clear whorl feeble axial riblets make their appearance, which increase 

 in strength up to the last two-tenths of the last whorl, when they 

 again fade out. These axial cords are arranged in a more or less 

 zigzag pattern. Below the summit of the last turn, particularly 

 toward the aperture, there is a slightly concave area. The last part 

 of the last turn is marked by slender spiral threads. Suture of all 

 but the last whorl strongly impressed; on this it is rendered less 

 conspicuous by the appressed summit of the last turn. Periphery 

 well rounded. Base strongly inflated, well rounded, rather narrowly 

 openly umbilicated, with a feeble cord marking the outer edge of the 



