DESCRIPTIONS OF GENERA AND SPECIES. 285 



has a broad, shallow, curved indentation in the centre ; 

 leaving the corners as large, paired, rounded lobes ; 

 thus the whole creature is somewhat heart-shaped. 

 Notogaster rather flat ; with two irregular, longitudinal 

 furrows about midway between the median line and 

 the lateral margin ; they are only due to the action of 

 the dorso-ventral muscles, and alter in detail from 

 moment to moment; in dead specimens, or preparations, 

 they are usually entirely lost. The mandibles (PI. 

 XVIII, fig. 7) when seen from above seem to curve 

 inward and be sharp-ended, so that the two look as if 

 they formed a pair of horizontal nipping jaws ; this is 

 however only an accidental appearance, when dissected 

 out they do not disclose any special reason for it ; they 

 are of the type usual in the family, but the chelate 

 portion is smaller than usual and its moveable arm 

 deep and strongly curved ; it is tridentate ; the fixed 

 arm is quadridentate, or rather the terminal tooth is 

 bifid. The palpi (PL XIX, fig. 2) have the first and 

 second joints of about equal length, the third shorter ; 

 the first is much thicker than the second, is strongly 

 curved, and increases a little toward its distal end ; it 

 bears a single hair springing from a notch near the 

 distal end of the joint ; there are two hairs about the 

 middle of the second joint. The third joint is the 

 thinnest; it bears two papillse, presumably sensitive, 

 on its actual distal end ; the lower is slightly the 

 longer. Haller says that the palpus is five-jointed; 

 this does not seem to me to be correct. There are a 

 pair of hairs, near together and near the median line, 

 projecting over the rostrum and reaching a little 

 beyond the tips of the palpi and mandibles. About 

 as far back as the coxae of the second pair of legs 

 there is a transverse line of four largish hairs on the 

 notogaster, and in a line with the inner pair of these 

 are three other pairs further backward ; the two hairs 

 of each pair separate rather more widely as they get 

 nearer to the posterior margin. There are five hairs 

 on each lateral margin ; two of which are between the 



