OYCLORHAPHA SCHIZOPHORA. 
615 
form only an inconsiderable portion. The whole group is sometimes 
also known as Muscaridae, Muscidae, or as 44 Muscidae sensu lato 5 ’ 
(sensu lato meaning 4 4 in a 
wide sense,” or 44 speaking 
broadly ”) as opposed to 
44 Muscidae sensu stricto ,” i.e ., 
the family Muscidce (House¬ 
flies, etc.). The primary 
division of this unwieldy 
assemblage of species is based 
principally on the distance 
between the eyes in the male 
as compared with the female, 
the size of the squamae, and 
the shape of the 1st posterior 
cell. This gives us two large 
groups. In the first the eyes 
in both sexes are wide apart, 
the 1st posterior cell is almost 
always quite open, and the 
squamae (especially the lower 
squama, occasionally called 
a 4 4 calyptron ’ ’) are generally very small or absent. These are the 
Acalyptrate Muscoids. Many of them are injurious to plants. 
In the second large group the eyes in the male are nearer together 
than in the female ; the 1st posterior cell is almost always much 
narrowed or closed, and the squamae are large and well developed. These 
are the Calypirate Muscoids. Many of them are injurious to animals. 
Fig. 407— Head of muscoid fly (from 
TOWNSEND). V. VERTEX. F. FRONT. L. FRON¬ 
TAL LUNULE S. FRONTAL SUTURE. A. THIRD 
JOINT OF ANTENNA. PL. PALPI. P. PRO¬ 
BOSCIS. 
The view most generally taken is that the Acalyptrates represent 
a less highly-specialised condition than do the Calyptrates. The two 
groups are certainly closely related, and though the family 
Anthomyiidce is generally included in the Calyptrates, because the 
squamae are well developed and the male eyes are frequently near 
together, it has the 1st posterior cell quite open as in Acalyptrates, 
and in some other respects shows that there is no real line separating 
the two divisions. Because of this open 1st posterior cell, a character 
easily recognised, and also because many of the larvae live after the 
