106 PROCEEDINGS OF THE NATIONAL MUSEUM. 



Terebrantia. — In the Terebrantia each segment except the first and 

 the last three is composed of a broad dorsal plate reaching- to the 

 sides, a somewhat narrower ventral plate, and one or two very narrow 

 plates on each side connecting these. Jordan states that one of the 

 two pleural plates comes from the ventral, the other from the dorsal 

 plate, but the dorsal pleural plate is sometimes wanting or indistinct. 

 The dorsal plates of segments, two to seven inclusive, are usuallj^ 

 strengthened, especially in the Terebrantia, by a chitinous ridge 

 along the inside somewhere in the anterior third, and this appears 

 externally as a darker, narrow stripe on these segments. The first 

 segment has a well-developed dorsal plate covering the hind part of 

 the oblique metathorax, and small side plates are present in some cases, 

 while the ventral plate is so short and small as to be easily overlooked. 

 In the females the ventral and pleural plates are wanting upon seg- 

 ments nine and ten, the broad dorsal plate bending around the sides 

 and approaching beneath to form the sheath for the ovipositor. In 

 both sexes all the segments are similar except the last two or three, 

 which in the females usuall}^ form a more or less sharp cone, while in 

 the males, as a rule, the end is bluntly rounded; only a few species 

 are formed alike in both sexes. 



Spines. — Each segment bears, as a -rule, but few spines, which are 

 small upon the anterior segments, but increase in size and prominence 

 posteriorly. These are most prominent upon the sides of the seg- 

 ments and especiall}^ around the last two, where they are called anal 

 spines and are frequently very long and stout. In some species, as 

 Quaintance has observed (454), these stout anal spines are the weapons 

 of offense and defense. 



Tuhullfera. — In this suborder all but the first and the last one or two 

 segments are formed alike. Each is composed of only a dorsal and ji 

 ventral plate joining at the sides by an indistinct suture. The ventral 

 plate of the first segment is onl}^ slightly, if at all, developed, while the 

 terminal segment appears to be a simple cylinder or tube and is foi'med 

 alike in both sexes. The dorsal plate of the first segment, in some 

 species, is drawn out anteriorly into a rounded projection, attaching to 

 the metathorax, and on each side of the projection is a separate side 

 plate. The arrangement and relative development of the lateral spines 

 is much the same as in the Terebrantia. As a rule, upon the dorsal 

 plates of segments two to seven inclusive, on each side at about one- 

 fourth the cross diameter of the segment from the edge, there stands 

 a pair of peculiar, inwardly bent, acute spines, and outside of these 

 there is frequently a segmental row of much longer, straight, blunt 

 spines. These dorsal spines appear to serve entirely for the confine- 

 ment of the wings when at rest. The last segment bears at its tip a 

 circlet of long, slender hairs, usually as long as, or longer than, the 

 segment itself. 



