72 THE AMEKICAN MONTHLY [March, 



Lithobotrjs stiligera. Lithobotrys nidus pendulus. 



adspersa. cribrosa? 



gemmata. 



Now, just count up the number of genera and species in this 

 list and see the significance of it. Of the 282 species figured by 

 Ehrenberg as found in this deposit, here ai^e 136, or nearl}^ one- 

 half; of the 43 genera, here are 39, or all but four. How is that 

 for one summer's work.'' Need I say that I was thoroughly satis- 

 fied with it.'' I will not undertake to say that all of those species 

 are named correctly. It will be noticed that in about a half a 

 dozen instances I have put a question-mark after them. And 

 possibly there are others that are doubtful or wrong. But the 

 point is this, that, unless I am very much mistaken, they are 

 either right or they are not given by Ehrenberg — in other words, 

 belong to the 141 species figured by Mrs. Bury, or to the 80 

 species which Haeckel estimates that this deposit contains over 

 and above the 423 figured by them both. And in addition to these 

 that I have named there are on these slides of picked forms, be- 

 sides duplicates, about 100 species that I have not as yet been 

 able to place at all. In some cases I could not even be sure of 

 the genus. As to the genera given in the above list, however, I 

 am confident that, with scarcely an exception, they are correct. 

 What better material, therefore, could a man ask for than this 

 same Barbadoes earth .'' But these 136 species did not all come 

 from one locality. They represent no less than five. Springfield 

 and Malvern Hill, however, furnished 32 out of the 39 genera, so 

 that the material from those two localities will be all that the 

 student requires to enable him to study the genera very satisfac- 

 torily. And when he has found all those 32, if he will take the 

 trouble to drop me a line, I will send him some material that 

 will supply two or three genera more. 



On Some Minute Magnetic and Hyaline Spliernles Found in 

 Terrace Dust. 



[From Bulletin of the Microscopical Society of Calcutta ] 



In the accompanying figures will be found illustrations of some 

 very minute particles of a glassy nature which were first col- 

 lected by Mr. C. Blechynden, of Calcutta, by means of a magnet, 

 in the dust gathered upon the flat-roofed houses of that city, 

 some of them at a considerable height. He suggested that they 

 might be of meteoric origin. Mr. W. J. Simmons made draw- 

 ings and prepared the following descriptions. He was inclined 

 to agree to the theory of meteoric origin on account of the 

 rounded, smooth surfaces, glassy appearance, and magnetic char- 

 acters — properties that would characterize molten cosmic mate- 

 rial falling through the atmosphere. He said : 



