248 INSECTS. SYPHONAPTERA. 



P. cermcalis, Lat. Cinereous, with the places where the stigmata 

 are placed brown or blackish ; lobes or divisions of the abdomen 

 rounded. Found on the heads of the human species, and parti- 

 cularly children. Lat. Gen. i. 168. 

 The males of this and the preceding species have at the posterior extremity of the 



abdomen a small scaly and conical projection, probably the sexual organ. The P. 



Nigritarum of Latreille, of a deep black colour, rugous, with the head large and of 



a triangular form, is probably only a variety of P. tiumaniis. 



P. bufali, Lat. Smaller than the P. humanus, with short antennae ; 

 head small ; body of a deep yellow, with brown lines, and five 

 tubercles on each side of the abdomen ; hooks of the tarsi very 

 long. Found on the buffalo at the Cape of Good Hope. 



ORDER III. SYPHONAPTERA, Lat. 



De Geer. 



Body compressed ; mouth with a sucker of two pieces inclosed 

 between two articulated laminae, which united, form a rostrum 

 or proboscis, either cylindrical or conical, and of which the 

 base is covered with scales. 



These characters distinguish this order from all the others, even that of the He- 

 miptera, to which they approach the nearest, and in which Fabricius had placed these 

 insects. They besides undergo a true metamorphosis, analogous to that of insects 

 with two wings, as the Tipularia. This order is composed of a single genus, the 

 Pulex of Linnaeus. 



Gen. PULEX, Lin. 



Body oval, compressed, divided into twelve segments, of which 

 three compose the thorax, and the others the abdomen ; feet 

 six ; no wings ; a jointed rostrum of two plates inclosing a 

 sucker. 



The head in this genus is small, much compressed, rounded above, truncated and 

 ciliated before. On each side is a small rounded eye, behind which in a hollow is 

 discovered a small moveable body covered with spines. At the anterior margin, near 

 the origin of the rostrum, are the antennae, scarcely so long as the head, and com- 

 posed of four almost cylindrical articulations. The sheath or rostrum has three 

 joints. The abdomen is very large, and each of its segments is divided into two, or 

 formed of two laminae, the one superior the other inferior. The feet are short, par- 

 ticularly the last, proper for leaping, spinous, with the thighs and haunches large, 

 and the tarsi composed of five articulations, of which the last is terminated by two 

 elongated hooks. The two anterior feet are inserted almost under the head, and the 

 proboscis is between them. The female lays twelve eggs, white, and slightly viscous. 

 From these are produced larvae without feet, much elongated, similar to small worms, 

 very lively, and rolling themselves in a circular or spiral form, or vermicular when 

 in motion. They are at first white, afterwards reddish. Their body is composed of 

 a scaly head, without eyes, bearing two small antenna?, and thirteen segments, with 

 small tufts of hair and two kinds of hooks at the end of each. Their mouth has some 

 small moveable appendages, of which the larvae make use in pushing themselves 

 forward. After remaining about twelve days under this form, they inclose them- 

 selves in a small silky cocoon, where they become pupas, and from which they de- 

 part in about twelve days more in their perfect form. 



P. irritans, Lin. The Common Flea. Chestnut-brown^, the feet 

 of a colour less deep ; segments bordered with short and stiff 

 hairs. Shaw, vi. pi. 122. 



