NOTHRUS BIVERRtlCATUS. 5l3 



slightly concave while the lateral parts of this margin 

 are occupied hij two very large, almost square projec- 

 tions or warts, which are directed backward, but, 

 being slightly larger at their distal than their proxi- 

 mal ends, are nearest together distally ; the transverse 

 sections of these projections would be roundish; 

 they are usually truncated, or somewhat hollow at 

 the ends ; and from near the middle of the truncated 

 end springs a small apophysis bearing a small, 

 very sharply curved, villous hair. Lateral margin 

 straight in general outline, but with an irregularly 

 undulated edge. The general level of the notogaster 

 is flat, but the margin is decidedly raised, except pos- 

 teriorly, the exterior edge being nearly the highest 

 point. A more or less oblong space in the median 

 line of the notogaster is bordered on all sides by an 

 ill-defined, slightly-raised ridge, somewhat curved ante- 

 riorly and posteriorly, more straight laterally; but 

 there is a slight constriction in the lateral ridges near 

 which they are joined by a faint transverse ridge, and 

 a diagonal ridge runs outward and backward from each 

 of the posterior corners of the oblong. Three small 

 chitinous apophyses, each bearing a very small, curved, 

 villous hair, stand almost upright just outside each 

 side of the oblong ridge, the first placed close to the 

 anterior corner of the oblong, and the third in the 

 before-named constriction ; the first and second of these 

 apophyses are nearer together than the second and third. 

 A similar apophysis and hair are placed just behind the 

 middle of the diagonal ridge. Outside the lateral parts 

 of the oblong ridge the abdomen is concave, and then 

 rises again, forming a broad, gradually raised margin; 

 this bears a few irregular, more or less transverse 

 ridges, and also (on each side of the body) three small 

 chitinous apophyses, each carrying a short, curved, 

 villous hair ; the apophyses do not project beyond the 

 lateral margin of the body. The pore of the expulsory 

 vesicle is near the last of these apophyses, but a little 

 nearer the median line. There are six similar apo- 

 voL. II. 33 



