556 Notes in Natural History. [Dec. 



The following list will serve to shew clearly why, in spite of the vast increase of 



the spiders, they do not cause that annoyance which the number would at first lead 



one to expect. 



A single cell contained, 4 spiders. 



f 1st cell 21 1 



A nest of two cells contained, \% a ce ii' o 2 \ =53 spiders. 



Ad °- d °- d °- {2nd cell; ::::.'. %\= bz s P iders - 



Ado. do. do. J ^ l d Jgj» • • ; ; ; ; } 3 } =30 spiders. 



Total, 140 

 Again, another insect of a fine blue colour builds a nest of 4 or more cells, one 

 of which I also give as an example, viz. 



1st cell, 23" 



2nd cell, 15 I, 



A nest of 4 cells contained, - 



3rd cell, Pupa ^~ 38 s P iders ' 



_4th cell, Pupa. 



The form of this last nest is the same as the foregoing, but I do not think the 

 insect is of the same genusf. 



Thus, however, we have more than 178 spiders killed by 5 insects alone ; conse- 

 quently, the increase of the species will be little more than equal to the consump- 

 tion. 



Of the insect itself I shall give you a description in some future paper, together 

 with that of several others which I have collected. 



I may add, however, that the cell is often built and stored with spiders in less 

 than an hour. 



I shall now proceed to make a few observations on the difference in several 

 scorpions which I have examined. 



In all the authors that I have hitherto had an opportunity of consulting, I find 

 the number of teeth, in the pectinated plates on the abdomen of these animals, 

 taken as one of the distinguishing marks of species. 



This has confused me not a little, as I have lately examined upwards of 30 scor- 

 pions of different sizes, scarcely one of which agreed in the number of these teeth, 

 and yet, setting this aside, they are the same in colour, in the number of eyes, and 

 are often found together in the same holes. 



In many instances I found one tooth less on one side of the pecten, than on the 

 other side, but this deficiency was generally (though not always) supplied by a knob 

 or rudiment of a tooth, which if counted as such made the plates correspond. 

 The deficiency was almost always at the inner end of the plate. 

 The following catalogue will perhaps shew the differences, better than I can de- 

 scribe them. 



No. 1. A scorpion with 15 teeth in the right pecten, 14 in the left pecten, and 

 a rudiment of a tooth on the left plate. Eyes 8 in number. Colour dark 

 livid-green ; tail and forceps brownish ; legs and poison-sack brownish straw- 

 colour. Length 3£ inches. Scorpio afer ? 



f Probably a species ofpompilus, or some other genus of pompilida. I. T. P. 



