1911.] NATURAL SCIENCES OF PHILADELPHIA. 583 



a half whorl long, and immersed, as in adults. A shell of 6h whorls 

 measures: alt. 9|, diam. 15| mm. At this and earlier stages the 

 axis is perforate. This species, commonly known in collections as 

 S. jayana, inhabits the region of Mandeville in Manchester, where 

 it is very abundant and generally dispersed. The types are 100,868, 

 A. N. S. P., from the ridge near Lincoln. They were catalogued as 

 S. jayana in our former paper (these Proceedings, 1910, p. 517). 



Besides the several differences noticed under S. jayana, the last 

 whorl is both deeper and broader in this species, in its fullest devel- 

 opment projecting beyond the general outline of the side, and appear- 

 ing somewhat disproportionately enlarged beyond the preceding 

 whorls. The adolescent stages are even more distinct from corre- 

 sponding stages of S. jayana than the adult shells. With several 

 hundred shells before us for study, we find the differential characters 

 of S. adamsiana remarkably constant. 



Named in honor of Professor C. B. Adams, whose Contribu- 

 tions to Conchology form the foundation of Jamaican malacology. 



Sagda montegoansis n. sp. Plate XLIII, figs. 13, 14. 



The shell resembles S. adamsiana in shape and the internal lamellce, 

 but it is smaller; the last whorl is less convex above, more flattened 

 below, the suture ; the aperture js decidedly higher, the basal margin 

 being more deeply curved. The surface has a varnish-like gloss, and 

 under the compound microscope shows no minute sculpture; the 

 last two or three whorls are only weakly, irregularly striate. 



Alt. 20, diam. 23 mm.; 9 whorls. 

 " 21.1, " 21.4 " 9i " 

 " 17.2, " 21 " 8 



Orange Hill, Montego Bay; types No. 104,452, A. N. S. P., col- 

 lected by Dr. A. P. Brown, 1910. 



This is probably the form listed from Montego Bay by Messrs. 

 Henderson and Simpson as S. epistylium Mull., 3 but, as noted above, 

 that is not a Jamaican species. 



Young shells, down to 4f whorls, diam. 9 mm., are imperforate. 

 By breaking down a shell it appears that only about two whorls fol- 

 lowing the embryonic stage (of 1^ whorls) have the axis perforate. 

 The perforate stage is therefore much shorter than in S. adamsiana. 



S. montegoensis differs from S. spei by having the basal lamella 

 nearer the periphery, being situated as in S. adamsiana. It was 

 found in great profusion. 



3 Nautilus, VIII, p. 2, No. 22. 



