30 TERTIARY INSECTS OF NORTH AMERICA. 



this work, have not been critically studied. A single caterpillar has been 

 found, and the structure of its skin has been studied by Dr. C. S. Minot, 1 

 but without any very satisfactory results. 



No Hymenoptera have yet been described. About a dozen specimens 

 are referred to Apidse and Andrenidae ; several species are represented, but 

 most of them are badly preserved ; the largest appears to be a Bombus. 

 Of Vespidffi and other large wasp-like Hymenoptera about seventy or 

 eighty specimens have been found, referable to about thirty species, one of 

 which is a large Scolia or allied genus ; several are Sphegidaj, including an 

 Ammophila; one, which seems to be a Polistes, shows traces of a blue- 

 green metallic tint; another, apparently one of the Pompilidse, represents a 

 species with a large subapical fuliginous spot on the wing; another, perhaps 

 of the same family, has a circular clear spot in the center of the wing, sur- 

 rounded with fuliginous. The ants are the most numerous of all insects at 

 Florissant, comprising, perhaps, a fourth of all the specimens; they form 

 more than three-fourths, perhaps four-fifths, of all the Hymenoptera ; I 

 have already about four thousand specimens of perhaps fifty species (very 

 likely many more) ; they are mostly Formicidse, but there are not a few 

 Myrrnicidse and some Ponerida?. I have noticed no Mutillidse. Iclmeu- 

 monida; are very numerous ; of minuter forms, having an expanse of wing 

 of less than a centimeter, there are nearly two hundred specimens, unusually 

 well preserved ; judging from a cursory examination they are exceedingly 

 numerous in species, perhaps eighty all told, and many genera are repre- 

 sented; the larger forms, whose wings expand more than a centimeter, are 

 even more numerous both in species and individuals, and most of them are 

 very fine, including a great variety, among which are especially noticeable 

 a good assortment of species of Pimpla and allied genera ; I have looked 

 in vain for Pelecinus, or any long-tailed Rhyssse or Thalessae. The Bra- 

 conida-, Chalcididse, Cynipidaj, and Chrysidre, exceedingly few fossil spe- 

 cies of which have ever been described, are very abundant, but have not 

 been fairly separated from eacli other and from other small species; 

 together they number nearly two hundred and fifty specimens and probably 

 fifty species ; among others there is a Chrysis, showing metallic green 

 reflections on the abdomen, and also more than half a dozen species of 

 Chalcididaj, with expanded femora, represented by over twenty specimens. 



' Arch. f. mikr. Anat., vol. 28, pp. 46-47, 1686. 



