96 
ENTOMOLOGICAL SOCIETY 
OCTOBER 6, 1887. 
Nine persons present. President Howard in the chair. 
Mr. Ashmead read the following paper : 
A PROPOSED NATURAL ARRANGEMENT OF THE HYMENOPTEROUS 
FAMILIES. 
BY WM. H. ASHMEAD. 
A natural arrangement of the divisions and families of the Hymenoptera, 
according to my views, differs so materially from that proposed by Mr. 
E. T. Cresson in his recent excellent work, " Synopsis of the Families and 
Genera of the N. A. Hymenoptera," that this early opportunity is taken to 
draw attention to them while that work is fresh before the entomological 
world. 
The division of the order into two sections Hymen, ditrocha and Hymen, 
monotrocha -is, I think, a natural one; but the arrangement of the fami- 
lies by Mr. Cresson is, in some respects, very unnatural, and fails to show 
their relationship. 
The section monotrocha I consider to contain the highest types of the 
order, and hold with Dr. A. S. Packard that, among the family Apidce, 
are found the most highly specialized forms. 
Beginning therefore with this family, I think a very natural sequence of 
the families can be shown leading into the Hymenoptera ditrocha as fol- 
lows : 
HYMEN. MONOTROCHA. 
ANTHOPHILA. 
DlPLOPTE RYGI A . 
FOSSORES. 
t Apidae 
1 Andrenidae 
I Masaridae 
\ Eumenidae 
^ Vespidse 
f Crabronidae 
Pemphredonidae 
Mellinidae 
Philanthidae 
Nyssonidae 
Bembecidae 
Larridae 
Ampulicidae 
Pompilidae 
Pelecinidae 
Sphecidae 
Scoliidae 
Sapygidse 
Mutillidae 
