E. IMPERIALIS. — GEN. CHARACTERS. 65 



canals, visible through the dermal layer, reach 1 inm. or slightly- 

 more in diameter. 



The cuff (PI. II, fig. 8) is thin and of varying width owing 

 to the irregularly undulating character of the edge-line. The 

 width also varies with the size of the specimens. In the largest 

 individual before me (spec. L of the list on p. 62) it is 11-20 mm. 

 as measured on the upper surface ; 4-10 mm. in a specimen (G) 

 478 ram. high ; and only 2 mm. in a specimen (C) 250 mm. in 

 height. The free edge may show at places the same interrupted 

 fringe of marginalia as those found on certain lappets of the 

 parietes. The fringe is however of inconstant occurrence. The 

 surface of the cuff presents a close-grained appearance unless 

 injured. 



The sieve-plate (PI. II, fig. 8) is usually arched like a watch- 

 glass, but the convexity ma}^ in some individuals be more strongly 

 pronounced than in others. The entire structure appears rather 

 frail owing to the comparatively thin beams and large meshes. 

 The latter, in shape triangular to polygonal with rounded angles, 

 are however of variable size, the larger ones measuring as much 

 as 7 mm. across. Some of the beams are scarcely Y4 mm. thick 

 at their middle, while others may be 1 mm. and more in 

 width. The majority are more or less flattened in an externo- 

 internal direction, the rest being more or less laterally com- 

 pressed. The nodes are frequently thickened in a knot-like 

 manner or widened into plates of considerable size. As in 

 E.. aspergillam , the entire sieve-plate presents the appearance of 

 being divided by the stronger beams into a number of primary 

 fields and these again subdivided by weaker beams into the in- 



