( xlviii ) 



The lat(M-al iirocesses {p, Tl. I>X1. f. 0— 11 ; PI. LXII. f. 1—5) arc designated 

 "pilifer" by Kellogg*), and are often erroneously considered to be homologous 

 to the niandildes. Tiie normal jnlifer is a curved obtuse process, concave and 

 flattened on the inncrsidc, and is licset on tiie inner surface with a great number 

 of long stiff bristles wliicii jiroject over the base of the tongue, which they 

 touch. Tiie pilifer and its bristles undergo various modifications. The bristles 

 become modified into scales, either partly or all (PI. LXI. f. 11), or they 

 become fewer in number and disappear finally nearly completely (PI. LXI. f. 10). 

 At the same time the pilifer may become shortened and lose the appearance of 

 a process, Leing represented in the most reduced state known to us ])y a broad 

 obtuse projection (PI. LXI. f. Id). Two other modifications are represented by 

 PI. LXII. f. 4. 5. In fig. 5 the pilifer {p) is almost stalked, and projects far 

 bej'ond the mesial lobe, which is large. In fig. 4 the whole epistome is 

 enlarged together, jiroduced forward, the pilifers being close together and very 

 Lroad, and i)roj('cting little beyond the mesial lobe, which is very small. 



Quite different from these modifications is that observed in all the species of 

 Choerocampinae, and only in this subfamily. PI. LXII. f. 2 represents a species 

 of Celerio : the pilifer {ji) is long, somewhat twisted, and the apical portion 

 is clothed inwardly with short bristles, wliile the proximal portion bears the 

 ordinary long bristles, the two kinds of bristles contrasting very strongly with 

 one another. This character is of surprising constancy ; its significance in 

 classification will be understood, when the characters of the palpus and antenna 

 are taken into consideration at the same time. 



Between i)ilifer and eye, supporting the former laterally, there is a more or 

 less triangular projection, which is an enlargement of the brim which separates 

 the eye from the large labial cavity of the underside of the head. We term 

 this projection " geual process " {gp of PI. LXI. and LXII.). The upper 

 portion of this genal i)rocess is often distinctly separated by a suture, and 

 corresponds to the mandible {;md, PI. LXII. f. 4), as pointed out by Kellogg, 

 /. c. The genal process is very large in Macroglossum (PI. LXI. f. 0), Sesia, 

 and allied genera, reaching often to the tip of the pilifer. In the Choero- 

 campnnae (in all of them) it is smaller than anywhere else (PI. LXII. f. 2), 

 not showing in a lateral view the distinctly triangular form observed in all 

 other Sphingidae with well-developed tongue. The suture between genal 

 process on the one side and labrum and clypeus on the other ends often (many 

 Ambulicinae) in a deep groove (J', PI. LXI. f. lU. 11). If we examine the 

 underside of the head after the removal of the labial paljii (PI. LXI. f. 7 ; 

 J/p is the groove in which the palpus is inserted), we find again the pilifer 

 and the genal process between eye and tongue, and observe below the pilifer 

 close to the tongue on each side a short process, dilated apically in the s])ecies 

 figured, which process is the remnant of the maxillary palpus (tnxp). It is 

 in most cases densely clotlied with long wiiite scales, which project beyond the 

 pilifer and genal process, being visible also in dorsal and lateral aspects of 



* Amer. NuUiralist xxix. Ip. 546 (1895). 



