SUBFAMILY DIASPIDINAE 227 



pair of lobes as the second incisura, and the next on each side 

 as the third incisura, the fourth, and the fifth. There is some dis- 

 crepancy as to the way in which the incisurae are numbered. 

 Most writers designate the median incisura as the median or 

 mesal and then number the others. A few writers number all the 

 incisurae and such writers always begin with the median. Most 

 of those who designate the first as the median do not designate 

 the next, the one between the median and second lobe of each side 

 as the second but as the first, the one between a second and third 

 lobe as the second, and the one between a third and fourth lobe 

 as the third, and so on. The median incisura is disregarded in 

 numbering the others. This method has not been followed. 



There are distinct thickenings associated with the incisurae 

 in certain species. These thickenings are located on the ventral 

 aspect and may be known as the densariae. A furrow extends 

 cephalad from the bottom of one or more of the incisurae onto the 

 ventral surface of the pygidium and one or both sides of each of 

 these furrows may be thickened. The thickenings are usually 

 club-shaped in outline with the clavate portion at the cephalic end. 

 The number of incisurae with densariae is usually less than the 

 total number of incisurae present. There are frequently more 

 pairs of densariae present than there are pairs of lobes. The 

 densariae are only rarely associated with the median incisura. 

 Comstock, who was the first to make use of the densariae in tax- 

 anomic work, called them incisions with thickened edges. They 

 were designated as paraphyses by Leonardi and Marlatt, but 

 these structures are confined to the dorsal aspect. The furrow 

 between the densariae, when there is one 011 each side of the in- 

 cisura, is frequently provided with a row of prominent oracera- 

 tubae. 



The broad or elongate semioval projections of the pygidial 

 fringe are the lobes. They are also known as trullae, pallae, 

 lobules, lamelles, or palette, and are also designated sometimes as 

 the primary lobes to distinguish them from the pseudolobes de- 

 scribed later. The lobes are typically arranged in pairs and sep- 

 arated by incisurae, although, through the absence of the mesal 

 incisura and the fusion of the mesal pair, this is sometimes appar- 

 ently untrue. The lobe on each side of the median incisura is 

 a median lobe, the two being distinguished as the median pair of 

 lobes. They are also known as the mesal or anal lobes. The lobes 

 cephalad of each median lobe are known collectively as the lateral 



