to 
DIPTERA. 
8. Cuterebra analis. 
Cuterebra analis, Macq. Dipt. Exot. ii. 3, p. 22, t. 2. f.5°; Brauer, Monogr. Mstr. p. 237. 57. 
Hab. Mexico?; Costa Rica; Panama, Volcan de Chiriqui 3000 feet (Champion).— 
Braziu}. 
A Chiriqui specimen in beautiful condition has been named as above by Prof. Brauer. 
4, Cuterebra approximata, 
Cuterebra approximata, Seth; in Lord’s Naturalist in Vancouver’s Island, ii. p. 338°. 
Hab. NortaH America, Vancouver’s Island}.—Mexico, Pinos Altos in Chihuahua 
(Buchan-Hepburn); GuareMaua, San Gerénimo (Champion). 
Two specimens: Prof. Brauer has seen one of these and believes it to be this little- 
known species. 
One other species of C&stride is recorded from Mexico :— 
Cuterebra atrox, Clark, Essay on the Bots &c., Addenda, p. 1 (1848); Brauer, 
Monogr. CEstr. p. 241. 9.—Mexico. 
Fam. MUSCIDA*. 
This family is by far the most extensive among the Diptera, and requires therefore, 
more than any other, to be divided into a certain number of subfamilies or groups. 
Such a division, however, presents great difficulties. Macquart separated the Muscide 
into two great sections, ‘Muscide Calyptere’ and ‘ Muscide Acalyptere,’ which he 
shortly indicated (Dipt. Exot. ii. p. 26) by the words: (1) tegule present; (2) tegule 
absent or rudimentary. However we define these terms, we ought not to imagine that 
they will form a sharp distinction; for the tegule, when the numerous species are 
examined, are found to decrease gradually in size till they finally disappear altogether. 
If we have before us a Muscid with fully-developed tegule, or another in which they 
are wanting, it is easy to decide in which section the insect ought to be placed ; but it is 
quite impossible to define the just limits of the two sections when these organs become 
so small that we should be inclined to call them rudimentary. Moreover, there are many 
examples in various genera, placed for good reasons in the first section, in which the tegule 
are still less developed than in other genera placed, for equally good reasons, in the second 
section. Nevertheless this division into two chief sections, ‘ Calyptere ’ and ‘ Acaly- 
pteree,’ is still in general use, and is adopted, without reservation, by Schiner in his ‘ Fauna 
Austriaca,’ ‘ Diptera,’ and ‘ Catalogus Dipterorum Europe,’ and also by other writers. 
The above remarks are equally applicable to the characteristics of almost every group 
(and to most of the genera also), into which these two sections are further divided, 
especially to those of the ‘ Calyptere.’ It is as if Nature, in creating numerous different 
forms answering to the same type, had brought forth all sorts of transitions. ‘The most 
ingenious entomologists have not yet been able to detect well-defined characteristics by 
which the groups and genera of this family may be surely distinguished from each other. 
* By F. M. van peR WULP. 
