578 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.47. 



narrowed toward the tip, which is bluntly rounded and armed with a 

 tuft of fine hairs, or with a short spine. Each hp is supported 

 around its margin by a chitin framework, which is articulated with 

 the chitin framework of the head, so as to allow the proboscis to 

 move freely backward and forward. The anterior margin of the 

 under hp around the mouth opening is also divided into two lamellae, 

 of which the inner one serves to contract the mouth opening while the 

 outer one is cut into a fringe along its free margin. The length and 

 thickness of this fringe varies considerably in different genera and 

 species. Usually it is more than half the width of the lamella, in 

 which case the fringe looks as if it were made of stiff hairs standing in 

 rows around the mouth opening. Again, the fringe may be so short 

 ffj} I that it can only be detected with difficulty, and 



hence appears to be lacking {Naohranchia) . 



When the proboscis is apphed to the host 

 for the purpose of drawing blood, this border- 

 ing fringe, together with the rest of the mem- 

 brane, is spread out around the tip of the 

 proboscis hke a sucking disk and probably 

 assists in obtaining the blood. 



There are no chitin rods nor any supporting 

 framework m this sucking border, as was 

 FIG. 2.-CR0SS SECTION OF PRO- clcarly showu by Kurz. 

 Boscis (DIAGRAMMATIC); upi, j^j^g mandihUs are rigid chitinous blades, 



UPPER lip; TO?, LOWER LIP. . • -i ,, , • i,, i ,i 



operatmg mside the proboscis, although they 

 originate on the ventral surface of the head, outside of it, and only 

 become inclosed when the edges of the upper and lower lips are 

 fastened together. The base of the mandible always remains outside 

 of the proboscis, inserted in a fold of the skin, and only the blade or 

 terminal portion enters the mouth tube through the triangular open- 

 ing at the base of the two Ups. The blade of the mandible reaches 

 to the tip of the proboscis, or may even project a little beyond the 

 latter. It is strongly flattened dorso-ventrally and brought to a 

 sharp edge along the two lateral margins. It is widest at the center 

 and tapers toward both ends; it is also frequently bent at or near 

 the center, so that the terminal portion curves in toward its feUow on 

 the opposite side. At the tip the inner margin is cut diagonally and 

 set with wicked teeth. 



Kurz distinguished three kinds of these mandible teeth; the first 

 he called principal teeth (Hauptzahne) . They are much larger and 

 stouter than the others, they usually curve backward, and they alter- 

 nate with the second kind, which he called intermediate teeth (Zwi- 

 schenzahne). These are very minute, triangular in shape, and they 

 occupy the base of the angles between the principal teeth. The 



