49 



it is to be employed in agriculture. Owing to its admixture with 

 rocks, ill which it occurs, it will be necessary to analyze each 

 lot of the ground mineral in order to ascertain the proportions of 

 sulphuric acid that will be required for its decomposition; the 

 analysis I have made being that of the pure mineral. 



Dr. Jackson, in conclusion, spoke of the great importance of 

 this substance in agriculture as manure. In England great 

 quantities of bones are annually ground up and used in agricul- 

 ture for the sake of this ingredient, which constitutes a small 

 proportion of them, and an extensive trade with South America 

 is carried on in importing the bones of the cattle killed there. 

 Even old battle fields have been dug over for the human bones 

 buried in them. The coprolites are also eagerly sought for, for 

 the very small amount of Phosphate of Lime which they contain. 

 Dr. Jackson expressed the hope that American farmers would 

 not neglect to avail themselves of so bountiful a supply of min- 

 eral phosphate of lime, a valuable material so readily within 

 their reach. 



Mr. Stimpson made some remarks on an Ascidian found 

 in Massachusetts Bay. 



It belongs to the family of Pelonaiadse, recently established by 

 Profs. Forbes and Goodsir, for two species found by them on 

 the coast of Scotland. They are referred to one genus, Pelo- 

 naia, to which the present species also belongs, making a third. 



P. arenifera. The body is elongated, clavate, of a brownish 

 color, and covered with grains of sand ; the apertures are placed 

 on two small, white, mammilliform protuberances at the smaller 

 extremity. It inhabits deep water ; the specimens were obtained 

 from eighteen fathoms, about ten miles east of the Boston light- 

 house. 



Mr. Desor called the attention of the Society to the sub= 

 ject of the Parallelism of the quaternary deposits of Europe 

 and America. 



The main difficulty which we encounter when we attempt to 

 parallelize the detrital deposits of Northern Europe and Ame- 

 rica with those of Switzerland, where they were first and most 



PROCEEDINGS B. S. N. H. 4 AUGUST, 185L 



