160 KANSAS UNIVERSITY SCIENCE BULLETIN. 



evidently in as intimate a relation to the median rod as the 

 lateral rods. Hence, there is possible a third theory: 



3. According to Lacaze-Duthier's view, there are "two 

 pieces forming the outer pair of rhabdites" (after Packard), 

 as seen in the figure illustrating his conception of the ideal 

 ovipositor. In Pachypsylla, one of these "pieces" might be 

 the rod and the lateral plate which connects basally with the 

 lever supporting the base of the upper valve, buv, and distally 

 with the tongues or sting-palpi. The median rod, then, might 

 represent the second of the "pieces," its two parts fused into 

 one. Thus rods and lateral plates, together with the sting- 

 palpi, would form one portion of the upper pair of valves 

 while the median rods represent the other paired portion, 

 fused. The sheath may also belong to the second piece of the 

 upper valves, as do the two pairs of small sclerites, sc 1 and 

 sc 2 (30-2). The levers supporting the bases of the lower 

 valves, blv, find their homologues in similar structures in the 

 honeybee, termed there simply "levers," which are the point 

 of attachment of muscles moving the sting. They have a sim- 

 ilar function here, serving to spread the styles. 



The ovipositor of the cicada has been described and figured 

 by Marlatt (1895). A rather superficial study of this form 

 from my own dissections has rendered the following facts 

 and hypotheses as to the homologies between this form and 

 Pachypsylla: There are found two pairs of blades, the dorsal 

 pair grown together, and the two pairs sliding on one another 

 by means of tongues and grooves much as I have shown to be 

 the case with Pachypsylla. The tips of the ventral pair of 

 blades are serrated for cutting purposes. These two pairs of 

 blades evidently correspond to the upper and lower valves or 

 styles ot Pachypsylla, though in the latter there is no need for 

 their tips to be modified for cutting, as the eggs are not de- 

 posited within plant tissue. In Cicada there is a very large 

 sheath surrounding the entire ovipositor, except for a slit be- 

 neath, which probably corresponds to the supra-anal plate, 

 Marlatt says, "The ovipositor is protected and covered when 

 at rest by two valves, which form a sort of sheath or scab- 

 bard." These second valves mentioned by Marlatt, which are 

 dorsad of the blades, proximad are broad, and made up of 

 chitinized and more or less membranous portions, and distad 

 are composed of two distinct and distally separable scabbards 



