VOL. VI.] PHILOSOPHICAL TRANSACTIONS. 645 



stops but fills up the hole, sometimes carrying in little clods, and sometimes 

 scraping dust with her feet, and throwing it backwards into the hole, going 

 down afterwards herself, to ram it close. Once or twice she flew up into a 

 pine-tree, which grew just over her hole, perhaps to fetch cement; when the 

 hole was full and even with the superficies of the ground about it, she draws 

 two pine-tree leaves, and lays them near the mouth of the hole, and flies away. 

 Not taking notice that she came any more in three or four days, we digged for 

 the caterpillar, and found it pretty deep. I put it into a box, expecting it 

 would have produced an ichneumon, but it dried away and nothing came of it. 

 We lately observed a sort of ichneumons, or rather vespae, which prey upon 

 several sorts of flies ; when they fly with them, they hold them by the heads, 

 and carry them under their bellies. These make holes a great depth in the 

 ground, in which they lay their young, and feed them with the flies they catch, 

 creeping backwards into the ground, and drawing the flies after them. I sus- 

 pect they may at first lay their eggs in the very body of a fly, but one fly being 

 not enough to bring the young one to its full growth, they feed it with more : 

 Their thecas are at last all covered over with the wjngs, legs, and other frag- 

 ments of flies. 



A Letter of Mr. Martin Lister, conjirmmg the Observation in N" 74, 

 about Mush-scented Insects; adding some Notes upon Dr. Swammer- 

 dam's Booh of Insects, and on that of Mr. Steno, concerning 

 Petrified Shells. N" 76, ^5. 228 1 . 



The former part of this paper is now unnecessary : the author's ideas relative 

 to fossil shells are singular, and therefore reprinted in his own words. 



Concerning petrified shells, I mean such shells as I have observed in our 

 English stone quarries. But, Sir, let me premise thus much, that I am con- 

 fident that you at least will acquit me, and not believe me one of a litigious 

 nature. This I say in reference to what I have lately read in Steno's Prodromus, 

 that, if my sentiments on this particular are somewhat different from his, it 

 proceeds not from a spirit of contradiction, but from a different view of nature. 

 First then, we will easily believe, that in some countries, and particularly along 

 the shores of the Mediterranean Sea, there may be found all manner of sea 

 shells promiscuously included in rocks or earth, and at good distances too from 

 the sea. But, for our English inland quarries, which also abound with infinite 

 number and great varieties of shells, I am apt to think there is no such matter 

 as petrifying of shells in the business (or, as Steno explains himself, p. 84, in the 

 English version, et alibi, that the substance of those shells, formerly belonging 



