TRIBE ASPIDIOTINI 385 



thing as to the segmentation of the pygidium of the aspidiotids. 

 The lateres may be entire, serrate, or crenulate, but all deep inden- 

 tations seem to be secondary in origin. 



The eeratubae in the Aspidiotini are very different and charac- 

 teristic in form and generally much more numerous in number 

 than in the other tribes. One of the most striking features is the 

 absence of altaeeratubae, which are so characteristic of the species 

 of the other groups. There may be oraceratubae located along 

 the pygidial margin but their eeratubae are not of the altaceratuba 

 type. Another striking feature is the absence of brevaceratubae. 

 The records are such that a definite statement can not be made, 

 but the presence of typical brevaceratubae in any aspidiotid is 

 very doubtful. The plates and pectinae are provided with lamacer- 

 atubae as in the other tribes, but they are often very long, some- 

 times two or three times as long as the pectina or plate which they 

 penetrate. The linaceratubae and clavaceratubae are found in 

 most species although there is considerable variation in number. 

 They are frequently fifteen to twenty times as long as wide, often 

 as long as the entire pygidium. Where they occur in considerable 

 numbers, their oraceratubae are often arranged in characteristic 

 longitudinal rows. The oraceratubae are usually placed in the 

 bottom of more or less distinct longitudinal furrows which usually 

 extend from or near the margin of the pygidium obliquely or longi- 

 tudinally across the pygidium. 



The vulva is usually located near the middle of the pygidium, 

 on a line drawn between the pregenacerores and postgenacerores, 

 but may be situated some distance cephalad of this point, on a 

 line drawn through the cephalic part of the pregenacerores. Where 

 the genacerores are wanting, it can generally be identified near 

 the middle of the pygidium by the radiating ridges of the cuticle 

 which extend from its opening. 



The anus is extremely variable in position. It is generally 

 located about half way between the middle of the pygidium and its 

 caudal end, but is commonly situated some distance caudad of the 

 vulva and is only rarely if ever superimposed over the vulva or 

 located cephalad of it. 



Genacerores are frequently present, while the typical number 

 of groups, five, is often present, there is more frequently four than 

 five groups present. The number of groups in a few species is 

 reduced to two. These are apparently formed by the fusion of 

 the pregenacerores and postgenacerores of the same side. The 

 only apparent explanation of the condition found in Selenaspidus, 



