542 Mr. D. Sharp and Mr. F. Miiir on the Comparative 



Family LYMEXYLONIDAE. 



Forms examined : Afractocerus valdiviensis 1 Ph., Chile. 

 A. africamcs Boh., Madagascar. 

 Figs. 149 and 150 Pi. LXVI. 



Atractocerus valdiviensisl (PI. LXVI fig. 149). 



Median lobe short and bulbous, drawn out to a short point at 

 apex where the median orifice is situate, base produced into two 

 short median struts ; median foramen at base. Tegmen forming a 

 shallow concavity in which the median lobe rests, and consisting of 

 two sclerites ; a distal bilobed (lateral lobes) piece, with two struts 

 encircling the median lobe and a curved basal-piece connected to 

 the lateral lobes by a membrane {cm 1). The internal sac appears 

 to be simple, which is exceptional when the median lobe is bulbous. 



We speak with much hesitation as to this and the following 

 owing to the bad preservation of the two individuals. The speci- 

 mens of this genus are too often found to be in a disastrous state in 

 collections. 



Atractocerus africanus (PL LXVI, figs. 150, 150^0. 



Median lobe long and slender with orifice at apex and foramen at 

 base. Lateral lobes complex, forming a pair of large complex lobes 

 joined together on the ventral aspect where they form a medial square 

 plate (o) deeply emarginate in the middle, and on the dorsal face 

 continue as two flat sclerites which join together at their bases where 

 the median lobes articulate (pa). The basal-piece forms a large shield- 

 shaped plate on the ventral face, the distal corners prolonged into a 

 pair of obtusely rounded projections. Internal sac undifterentiated. 



The anus of this species opens at the end of a large tube, wliich 

 lies over the aedeagus. 



These two types differ from one another and do not 

 approach to any of the other trilobe forms. We anticipate 

 that they will prove to be of important bearing. 



Family DASCILLIDAE. 



Forms examined : Ptilodactyla sp., Brazil. Bascillus 

 cervinus L., England. 



Figs. 151 and 152 PL LXVI. 



Ptilodactyla (not named in Brit. Mus.) (PL LXVI fig. 151). 



A trilobe form. Median lobe well developed, tapering to a fine 



point at apex ; median orifice on ventral aspect, forming a long dit 



