INSECT A. 303 



Gyropus NITZSCH. Tarsi uniunguiculate. Labial palps none. 



Of this genus only few species are known, which live on the Cavice and 

 the Sloth (Bradypus tridactylus) i. e. on American species of Mammalia. 



ORDER IV. Suctoria s. JSiphonaptera. 



Apterous, hexapod, undergoing perfect metamorphosis. Mouth 

 suctorial ; rostellum formed of two serrated laminge and a single 

 more slender seta, included in a bivalve articulate sheath. 



Family VII. Pulicidce (characters of the order are those of the 

 single family). 



Pulex L. [Characters of the order.] Body compressed. 

 Antennae short, with three or four joints, the last large, 'flat, 

 serrated, received in a small cavity and covered with a scale. 

 Maxillary palps with four joints, porrect. Posterior feet saltatory. 

 Tarsi with five joints. 



The order of sucking Insects, which contains the genus Flea, 

 agrees in the complete metamorphosis with the Diptera ; but the 

 oral parts have little resemblance. The flea is perfectly distin- 

 guished from the hemipterous sucking Insects not only by the 

 perfect metamorphosis, but also by the oral parts, by the presence 

 of palps for instance. DUGES first drew attention to four small round 

 plates, which are situated on the last two segments of the thorax, 

 and of which the posterior pair is the largest. These plates, which 

 in colour and substance do not differ from the rest of the horny 

 covering of the body, may be looked on as rudiments of wings. 

 The resemblance with the metamorphosis of the Hymenoptera, 

 especially in the pupa, together with the presence of these four 

 rudimentary wings, may serve to explain in some degree why an 

 inclination has prevailed to regard the suctoria as abortive hymen- 

 opterous Insects. 



There are two simple eyes, which in Pulex vespertilionis DUGES 

 are wanting. The sucker is inclosed by the flat labial palps con- 

 sisting of (three ?) joints, and is composed of two flat setae serrately 

 toothed on the edge and ribbed longitudinally in the middle (scalpella 

 KIRBY and SPENCE, mandibles), and a thin smooth thread of the 

 same length (ligula SAV.) There is no upper lip present, unless it be 





