NORTH AMERICAN DIPTEKA. 325 



and galea, shown at/, fig. 4. These are here completely divided, the 

 basal part of each broad, mostly chitinous, and forming more than half 

 a cylinder. Above this are two segments, representing the joints of the 

 galea, less chitinized, the basal segment largest, forming a shell, inside 

 of which is the lacinia, but outside of which is the palpifer, bearing 

 the maxillary palpi at its base. This lattei- piece, which may be stipes 

 rather than palpifer, is also produced and forms a piercing organ. 

 It passes outside of the galea until near the tip of the basal joint ; 

 here the cylinder formed by the segment is incomplete, and the pal- 

 pifer enters to join the remainder of the piercing mouth parts. The 

 lacinia is attached by a chitinous rod to this palpifer, and runs within 

 the galea for its entire distance. At e, fig. 4, the lacinia, palpifer 

 and maxillary palpus are shown separated from the rest of the mouth 

 parts. At fl, fig. 4, the tips of the lacinia and palpifer are shown, 

 greatly enlarged, to bring out the serrated armature. The palpus 

 contains on joint 2 a round pit connecting with a pocket of darker 

 colored cells, as shown at d, fig. 4. Central to the mouth is the 

 structure shown at c, fig. 4, composed of a broad basal plate, the 

 mentum, bearing a stout chitinous process, showing evidently its 

 paired character, especially at tip. These are the paraglossia, and 

 within the groove formed by these parts united at bottom, lies the 

 ligula. 



I omitted to state what fig. / distinctly shows, that the terminal 

 joint of the galea consists of merely a shell, not more than half a 

 cylinder, beset on the outer side with short hair, arising from fleshy 

 tubercles. In this insect I found the Dipterous mouth parts most 

 divided, and, so far as the galea is concerned in the condition most 

 nearly ap|)roximating that of the mandibulate mouth. What I term 

 the palpifer may be really the stipes, and the real palpifer may be 

 the basal segment of the palpus itself; but, as will be seen in Erax, 

 the palpi arise directly out of this part, and it is not a matter of 

 very serious import, for my present purpose, to settle this question 

 definitely. There is no outer covering of membrane to the mouth 

 parts, and this is a point that requires notice, because of the impor- 

 tant influence which that structure exercises upon the development 

 of the palpi. 



It may not be unnecessary to state that all the drawings made foi- 

 this paper were sketched by the use of the camera lucida, and that 

 the irregularities and lack of symmetry are faithful reproductions of 

 what is seen in the slide itself The image was thrown on a slightly 



