1880. 
131 
Dr. Muller assumes, as results from the tenor of some passages 
(especially one on p. 41, left column), that in the Blepharo ceridce, as 
in a great many other Dipt era, the eyes are contiguous in the male, and 
separated by a distinct front in the female. But it is just in this 
respect that the D lepharoceridce differ from most other Diptera ; their 
eyes are contiguous in some genera and separated in others, but when 
contiguous, they are so in both sexes, and when separated, likewise. 
The weight of this statement is qualified, it is true, by the circumstance 
that amongst twelve described species of Phphctroceridce, only four 
are known in both sexes ; of the other eight only the males are known, 
which execute aerial dances and are more frequently caught. It is 
possible, therefore, that the species observed by Dr. Muller differs 
from the cases hitherto known, and has the eyes contiguous in the 
male, while they are separated in the female. Moreover, Dr. Muller 
states explicitly that he examined the structure of the abdominal ap- 
pendages of both sets of females, and found them to be the same in 
both. If it had not been for this statement, one might have suspected 
that the female without mandibular organs was in reality a male, and 
that the male with contiguous eyes belonged to a different species. 
Another remark which suggests itself to me, is about the generic 
name of Dr. Muller’s species. Dr. Schiner described a male Paltostoma 
as having separated eyes ; Paltost. torrentium has them contiguous ; 
this would, perhaps, constitute a difference of generic importance. 
The statement, finally, that Paltostoma occurs in Europe, and has 
been found on Monte Rosa, is based upon some misconception. The 
JBlepharo cerid discovered on Monte Kosa is llapalothrix, a very abnor- 
mal genus in that abnormal Family ; it has nothing in common with 
Paltostoma but a superficial resemblance in the venation. Paltostoma 
has been found in South America and Mexico only, 
If this article should meet the eye of Dr. Muller, it will perhaps 
induce him to furnish us with more facts about this interesting question ; 
mature imagos should be caught, and the venation of their wings, as 
well as the structure of the genital organs, carefully compared. 
Err ors may easily occur. Thus, Mac-quart received from the same 
locality specimens with contiguous and separated eyes, and described 
them as sexes of the same species. It was found afterwards that they 
constituted different genera, and that the specimens with contiguous eyes 
( Blepharocera ) were the females, while those with separated eyes 
( Liponeura ) were the males ; exactly the opposite of what one would 
have expected. 
Persons desirous of more information about Blcpharoccridcc , I 
