23 



exceeds the upper lip in length, and the maxillae are still shorter than the 

 latter; all the setae appear hard and sharp."* 



The species of Bombyliidae which I have chosen for study is Bombylius major. 

 Its proboscis is about three times the length of its head (See PL 2, figs. 1 and 2), 

 and extends directly forward from the ventral side of the anterior portion of its 

 head, in such a position as to be parallel with any plane on which it alights. 

 Gerstfeldt 3 (p. 14) incorrectly regards the proboscis of Bombylius as extending 

 first directly downward, and then bending, knee-formed, forward. The pharynx 

 at the entrance of the head, turns slightly upward (fig. 3, ^>), but the proboscis 

 itself is straight. The tip of the proboscis is divided into two labellae, which 

 separate and press themselves, with a rubbing motion, upon whatever Bombylius 

 eats. When the labellae are separated the tip of the hypopharynx is visible (as 

 in fig. 2) between them. The basal half of the proboscis often appears split into 

 an upper and under portion. At each side of the base of the proboscis arises 

 a one-jointed palpus, at the base of which the maxilla can be seen (fig. 1, mx) 

 to pass downward and into the side of the proboscis, between the above-mentioned 

 upper and under portions. The different parts of the proboscis can be separated 

 from one another with dissecting needles, and are five in number, but their determ- 

 ination, as regards length, position, and homology, is better revealed by sections, 

 a series of which (fig. 1, a-l') are connected by dotted lines to the place in the 

 figure of the proboscis and its base, from which the sections, which are repre- 

 sented in the figures, were taken. As shown by these sections the mouth-parts 

 consist of three unpaired organs, labrum-epipharynx, hypopharynx, and labium, 

 and of a pair of maxillae with maxillary palpi at their bases. These parts will 

 be described in detail further on. The comparative length and size of the sepa- 

 rated labrum-epipharynx, hypopharynx, and maxillae, can be seen in the upper 

 portion of fig. 1, where they are represented in their proportionate lengths and 

 sizes, as compared with the entire proboscis figured below them. All the mouth- 

 parts of Bombylius are without art iculations and are more or less pubescent, altho 

 the hairs are very minute on the maxillae. (See fig. 4.) When at rest the 

 organs of the proboscis are thus arranged (Compare fig. 1, 17 and#): the hypo- 

 pharynx (h) lays in a groove on the upper side of the labium (I) and is covered 

 by the labrum-epipharynx ; beneath or at the side of the labrum-epipharynx (Ir-e) 

 are the maxillae (?n,) and maxillary palpi (mp). 



* " Vier Borsten - - die immer den Maxillen, der Oberlippe und dem hypopharynx 

 entsprechen, wahrend die Mandibeln mit der Riisselscheide verschmolzen sind besitzen 

 auch die Bombyliarien (bei Bombylius iibe.rtrifft der hypopharynx die Oberlippe an Lange 

 und die Maxillen sind noch kiirzer als letztere, alle Borsten aber erscheinen hart und spitz)." 



