112 BULLETIN OF THE 



There are several closely allied small forms found on our southern coast 

 which it may be well to differentiate, as without careful discrimination and 

 study they are liable to be confounded, as by Mr. Tryon, though they are 

 separated by what appear to be very constant characters. The species are 

 M. cerina Kurtz & Stimpson, M. cerinella Dall, M. citronella Dall, M. serga 

 Dall, M. atrostyla Dall, M. limonitella Dall, and M. ephamilla Bush. I have 

 been able to study typical specimens of all of them. They all have transverse 

 ribs, fine granulous or frosty spiral sculpture, and are distributed over very 

 much the same region. In order of size they run from citronella, which is the 

 smallest, through cerina, limonitella, serga, and atrostyla, to cerinella, which is 

 the largest. They have, in the same order, omitting the nucleus, five whorls, 

 up to atrostyla which has six, and cerinella which has seven. M. citronella is of 

 a brilliant yellow, cerina of a waxen white tending to ash color on the upper 

 whorls, but no lines of color or any tint on the columella or lip ; limonitella is 

 whitish, lineated spirally with yellow brown and often with some brown on 

 the outside of the canal or on the pillar; serga as far as known is pure white ; 

 atrostyla is variable as to its colors, ranging from yellowish white to dark 

 brown, wholly or in stripes and bands ; but the most typical form has a dark 

 purple brown shade just in front of the suture, the rest of the shell ashy, or 

 waxen white, except the pillar, which is very dark purple or almost black. All 

 the Antillean specimens I have seen are colorless. It may prove to be a larger 

 form of limonitella, which is the older name. M. cerinella is whitish toward 

 the vertex, ashy on the intermediate whorls, and with a tendency to orange or 

 flesh-color for the body whorl; it is never striped or spotted, and the pillar is 

 always like the rest of the last whorl. 



M. citronella has a very minute brown tilted nucleus followed by three tro- 

 choid larval whorls; a spire markedly shorter than the last whorl, with inflated 

 whorls ; twelve riblets, no varix, and a very faint sutural notch, while the suture 

 is distinct and not appressed. The four larval whorls are prettily marked 

 with transverse concave ripples. Lon. 6.25 ; last whorl, 4.25 ; lat. 2.5 mm. 

 (See Plate IX. fig. 5.) Off Sombrero, in 70 fms. 



M. cerina has a smaller larval shell with a less acute apex, the spire nearly 

 equal to the last whorl, with flattish whorls angulated at the periphery, nine 

 swollen riblets, no varix, the notch well marked and away from the suture 

 which is broadly appressed and undulated ; the canal is very short and the ribs 

 arched when they extend over the fasciole. where they usually fail. The nu- 

 clear whorls are smooth except the last, which has three or four nodulous spiral 

 lines on it. Lon. 6.75; last whorl, 3.75 ; lat. 2.1 mm. North Carolina to 

 Florida. 



M. limonitella has the spire but a trifle shorter than the last whorl, the 

 whorls rounded, and angulated behind the periphery, twelve narrow riblets, no 

 varix ; the notch shallow, deepest near the angulation ; suture hardly appressed 

 or undulated; canal not differentiate from the aperture ; ribs obsolete on the 

 fasciole, or, if present, arched in harmony with the lines of growth. Lon. 7.1 ; 

 last whorl, 3.7 ; lat. 2.5 mm. Florida. Fresh specimens show this to be a 

 February 11, 1889. 



