224 THE COCCIDAE 



They are also known as macropores and micropores. In the genus 

 Chionaspis and its allies, the number of oraceratubae on each side 

 of the meson is sometimes designated by the use of a formula in 

 the same way that the number of plates are sometimes indicated. 

 There are at least six types of ceratubae. 



The altaeeratubae are found in the Lepidosaphini, Diaspidiiii, 

 Parlatoriini, and Fioriini. They are the large broad cylinders, 

 the mouths of which are usually oblique and located at or near 

 the margin of the pygidium. 



The brevaceratubae are of the same general form as the alta- 

 eeratubae, but they never open at the margin of the pygidium. 

 Their oraceratubae are never oblique and they are always much 

 shorter and smaller in diameter than the altaeeratubae. They are 

 usually about as broad as long and their oraceratubae are generally 

 known as dorsal pores or dorsal tubular spinnerets. 



There is of common occurrence in the pygidia of the Aspidio- 

 tini long slender ceratubae in which the two sides are parallel or 

 nearly so. They are sometimes fifteen or twenty times as long as 

 broad. These are the linaceratubae, the wax ducts of Comstock 

 and others, and their oraceratubae are sometimes designated as 

 macropores. 



In the pygidia of the Aspidiotini, there is in addition to the 

 linaceratubae, other ceratubae which are as long or longer than 

 the linaceratubae, but in which the greater part of the tube is 

 reduced to a fine thread. The inner truncated end of these cera- 

 tubae which bears the bulla is much larger. This enlarged inner 

 end gives these ceratubae a distinct club-shaped or clavate appear- 

 ance and they are consequently known as the clavaceratubae. 



In addition to the linaceratubae and clavaceratubae, there are 

 other long slender ceratubae in the pygidia of most Diaspidinae. 

 These are the lamaceratubae. They differ from all other ceratubae 

 in that their oraceratubae are always located in the distal end of a 

 plate or pectina, projections of the pygidial fringe. 



The lateral portions of the segments of the preabdomen bear 

 projections which are known as bracteae. They are not only 

 similar in general form to plates or pectinae but are undoubtedly 

 their precursors and bear oraceratubae at their free end. The 

 ceratubae opening through the bracteae are paraceratubae. They 

 are, so far as observed, always short slender tubes that are ordi- 

 narily so slender and delicate as to be identified only with great 

 difficulty. 



