Nov., 1902.] Passalus Cornutus. 301 



anterior to the frons ,and is separated from it by a transverse de- 

 pression which does not extend completely across the head. The 

 clypeus is called epistoma when reduced in size. The gula (9) 

 occupies the posterior half of the median ventral portion of the 

 liead and is largely taken up with a rounded elevation which articu- 

 lates with the prosternum. Anterior to this elevation there is a 

 median depression with lateral elevations. The suture which sepa- 

 rates the gula from the sclerite lying in front of it is situated on 

 the anterior portion of this median depression and extends laterally 

 over the elevations on its sides. It is a well marked suture and is 

 called the gular suture (10). The submentum (11) lies in front 

 of the gula and is separated from it by the gular suture. It is 

 usually called the mentum. but since it is in contact with the gula 

 it is probably the submentum. It is deeply emarginated on its an- 

 terior border and free on its laterial borders. The posterior por- 

 tion of this free lateral border forms the inner botnidary of the 

 genal emagination into which the maxilla can be retracted. The 

 anterior emargination is occupied by the labrum (8'9'). The 

 compound eyes (4) lie on the sides of the head under the frontal 

 ridges and are divided into two nearly equal portions on their 

 anterior border by a posterior projection of the frontal ridge. 



THE MOVABLE PARTS OF THE HEAD. 



The antenna (2') lies just in front of the eyes under the an- 

 terior border of the frontal ridge. It has ten segments of which 

 the first is large and concealed by the frontal ridge. The follow- 

 ing six are almost equal in size, number 2, 3 and 4 being somewhat 

 smaller and all are slightly elongated anteriorly. The last three 

 are much larger and prolonged anteriorly, forming a pectinate 

 club. These three are not in contact with each other. The labrum 

 ( i') lies anteriorly to the clypeus between the mandibles. It is 

 bilobed and covered with stiff short bristles. It can be easily re- 

 moved for study. The mandible (3') should be removed for ex- 

 amination. It is flattened laterally and examined from the under 

 surface will be seen to bear a number of cutting spines. One of 

 these on the ventral border near the proximal end is articulated. 

 The maxilla (4' -7') can be removed easily for study by inserting 

 a pin into the posterior border of the genal emargination into 

 which the maxilla is retracted and pushing it out forward. It 

 should be examined from the dorsal surface. It consists of a long, 

 slender basal piece, the cardo (4') ; following this is a large median 

 piece divided longitudinally into an inner and an outer portion. 

 The outer piece is spindle shaped and is called the stipes (5'). It 

 bears on its anterior end a four-jointed palp (10'). On the inner 

 border of the stipes and extending beyond its anterior end is the 

 lacinia (6'). It bears many bristles on its free inner border and 



