256 INSECTA. 
mate to the last mentioned Anthraces, but according to that gentle- 
man the oral cavity is closed as in Cistrus, and the ocelli are want- 
ing. 
Our second general division of the ‘Tanystoma is charac- 
terized by a membranous proboscis, usually with a short stem, 
projecting but slightly and terminated by two very distinct 
and raised or ascending lips. 
The form of the head in the larve of the last Diptera of 
this division is variable: 
In some—Leptides—the wings are distant and exhibit se- 
veral complete cells. The antenne are not terminated en pa- 
lette. The palpi are filiform or conical. 
Sometimes these palpi are withdrawn into the oral cavity. 
The antenne have a fusiform termination or one resembling 
an elongated cone, with a little articulated stilet at the end(1). 
Tuereva, Lat. Meig.—zbi0, Fab. 
To which belongs the following species. 
T. plebeias; Bibio plebeia, Fab. Black, with cinereous hairs; 
abdominal annuli margined with white. On plants. 
The larva of a species of this genus—Vemotelus hirtus, De 
Geer—lives in the ground and resembles a little serpent. Its 
body is white and pointed at both ends. It changes the whole 
of its skin when about to become a pupa(2). 
Sometimes the palpi are exterior. The last joint of the 
antenne is either almost globular or reniform, or nearly ovoid 
or conical and terminated by a long seta. 
The tarsi are furnished with three pellets. They form the 
genus 
(1) This subdivision corresponds to the family of the Xylotoma of Messrs 
Meigen and Macquart. 
(2) Lat., Ibid., Fab., Meig. and Macquart. In the collection of Faujas, I saw a 
piece of schist that exhibited the impression of a species of this genus. 
