16 



PROCEEDINGS OF THE ACADEMY OF 



[Jan. 



in the open fields and in walls along the roadside, their only cover 

 being the walls or the low vegetation of the fields, and they are 

 all smaller than the Somerset and Swift Collection series. The 

 one exceptionally small specimen was adult, so far as development 

 of the lip was concerned, and in size would correspond to Pfeiffer's 

 variety which he calls L. aureola minor, being even smaller than his 

 dimensions for that form. But while it compares in size with the 

 Montego Bay forms, it is not at all like them in sculpture, resembling 

 the normal L. aureola of the island generally. It is evident, then, 

 that the normal L. aureola may vary in size in occasional individuals 

 down to that of the dwarfed or "runt" race found near Montego 

 Bay. This last race is a composite one, in about one-half of the 

 Orange Hill specimens and one-third of the Rose Mount specimens 

 a distinctive sculpture characterizes the forms. This has already 

 been described above. The minor diameter of the protoconch is 

 also somewhat less than in the normal forms of this species, this 

 dimension varies from 0.55 mm. in the Somerset and Swift Col- 



Fig. 4. — Lucidella aureola. 



Comparison of the width and height by whorls from 

 four different locahties. 



lection specimens to 0.50 mm. in the Santa Cruz Road specimens 

 and 0.45 mm. in those from Montego Bay. 



A comparison of the dimensions of L. aureola by whorls is given 

 in fig. 4, where these protoconch diameters are plotted along with 

 the heights. It will be seen that the diameters by whorls do not 

 show much variation in the four lots of specimens examined until 

 the third whorl is passed, but a marked falling off in the diameter 

 of the Santa Cruz Road and the Montego Bay specimens commences 

 with the fourth whorl, becomes still more pronounced in the fifth 

 whorl and culminates in the last whorl. As in the case of L. granu- 

 losa, there is a reduction in the number of whorls in the adult stage 

 in the case of the dwarfed Montego Bay forms which accentuates 

 the diminution in diameter after the fifth whorl. The number of 

 whorls is of course larger in the larger specimens from Somerset, 

 the Swift Collection lot and the Santa Cruz Road specimens, being 

 generally over six whorls, whereas the specimens from Montego Bay 



