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two small tentacles ; colour dark bottle-green, inclining to black. 

 Shell ; globose or conic, sometimes a little depressed, spirally 

 variously sculptured, the whorls being mostly rounded, in a few 

 instances slightly angled, last whorl sometimes very much pro- 

 duced ; umbilicus sometimes concealed ; aperture small, some- 

 what semicircular. 



The genus Stoastoma was founded by the late Professor C. B. Adams, 

 about ten years since, for the reception of a few exceedingly minute shells 

 inhabiting Jamaica, Porto Bico, and probably some other of the West 

 India Islands. As the name of the first discovered type, Stoastoma jnsum, 

 implies, they are like microscopic peas, globose and subdiscoidal in form, 

 with a small semicircular aperture, presenting good subgeneric differences, 

 and some marvellous varieties of sculpture. About twenty species, named 

 in honour of various conchological friends, were defined by Professor 

 Adams, but that number has been increased to eighty by Mr. Edward 

 Chitty, formerly of Jamaica, who has described his specimens in the Pro- 

 ceedings of the Zoological Society, and liberally deposited them, together 

 with the rest of his West Indian collection, in the British Museum. Mr. 

 Chitty's attention being specially called to the little Stoastoma Wilkin- 

 sonianum, by Professor Adams, whilst on a visit to Jamaica, he found 

 it to agree with a minute shell picked up by him in his garden some 

 time previously, and determined to search for more. " I ransacked my 

 garden," says Mr. Chitty, " and all round in vain ; for, as I now conclude, 

 it had been brought there accidentally, perhaps by a bird ; till at last I 

 crossed a deep ravine, a streamlet at the bottom of it, and got to one side 

 of what we call f Little Yallahs Hill/ which stands a good half-mile crow- 

 fly from my garden. There 1 found a spot, a slope on the hillside, with 

 crumbling fine dirt running, or sifting as it were, down it." In this dirt, 

 he goes on to relate that he found plenty of S. Willcinsonianum and other 

 new species, and continues: — "The formation of Jamaica being mostly 

 tertiary limestone, out of about a quart of such dirt as this I have taken 

 dozens and dozens of minute specimens of no less than thirty-one species, 

 besides larger ones which the naked eye could well see, — probably upwards 

 of fifty species from one quart of dirt altogether ! " 



Mr. Chitty means, doubtless, a quart of dirt made up from different 

 localities ; for in describing the geographical distribution of the Stoasto- 

 mata, he states that five or six species may be found to inhabit a certain 

 spot, and that you may search in vain for them outside a circumference of 

 about three-fourths of a mile. 



We give the species grouped according to Mr. Chitty, adopting his 

 genera as subgenera. 



