NEW MALLOPHAGA. 451 



noticeable on the sclerite when viewed from the ventral 

 side by means of transmitted light. It is much longer 

 than broad, and its widest diameter is in front of the 

 middle. Anterior to this the dorsal edges form a rounded 

 outline, but back of it they are a little concave and ap- 

 proach each other posteriorly. The posterior end is 

 narrow and rounded. The walls of the cavity are con- 

 cave, steeper in front and behind than elsewhere. The 

 bottom slopes a little downward posteriorly, so that the 

 cavity is deepest behind. Running longitudinally along 

 the bottom is a narrow groove; this begins in front at 

 the bottom of the anterior wall, and extends backwards- 

 from an aperture which is the opening of a duct into the 

 sclerite. 



To the sides of the shallower cavity are attached two 

 large, laterally compressed, chitinous, pyramidal struc- 

 tures, one on each side, whose ventral surfaces are not 

 quite so divergent as the walls of the cavity to which 

 they are attached, or perhaps better, from which they 

 arise. The bases of these are very wide, but dorsally 

 they become rapidly narrowed and pass upwards around 

 the oesophagus, or pharynx, as two chitinous bands. Their 

 dorsal ends are attached by large muscles to the dorsal 

 wall of the head. 



The sclerite is about as wide as long, or sometimes a 

 little longer. The dimensions of one specimen measured 

 are as follows: Length of the body, .097 mm.; width,. 

 .108 mm.; length of posterior projections, .02 mm.; dis- 

 tance which anterior processes extend in front of anterior 

 border of the main part or body, .0227 mm. 



The gland-like structures (plate lxii, figs. 1, 7 and 8) 

 before referred to, lie ventral to the sclerite, and the inner 

 halves overlap its outer portions (fig. 7). Their outer edges 

 also lie a little dorsal to their inner edges, so that they ex- 



