NEW MALLOPIIAGA. 



443 



ginal thickening and perpendicular to it, the latter lying 

 close to the edge, just back of the teeth. Near the base 

 of the maxilla on the inner side is attached a large muscle, 

 as large as the maxilla itself. This large muscle and the 

 strong teeth seem to indicate that the maxilla is not func- 

 tionless, but that it plays some part in the mastication of 

 the food. 



The mandibles (plate lxi, fig. 2) are the same in gen- 

 eral shape and position as those of Ancistrona gigas. 

 Those of the two forms present corresponding processes, 

 and in each they lie in a plane parallel with the head. 

 They are in both triangular in general outline viewed 

 dorsoventrally. 



The right mandible of Lcemobothrium has at its ante- 

 rior inner corner a large, strongly chitinized tooth, which 

 is a continuation inward and forward from the ventral 

 surface of a strong anterior thickening of the mandible. 

 Posterior to this is a second tooth, just as in Ancistrona, 

 continuous with the dorsal surface. This, however, in- 

 stead of being regularly rounded is in Lcemobothrium 

 very wide, especially at the base, and is of the form of a 

 truncated cone. The inner, or free end, is roughened 

 by several short blunt cusps. This tooth, however, very 

 evidently is the same thing as the posterior tooth of An- 

 cistrona; the positions on the mandibles are identical. 



From the inner posterior angle is a thick blunted pro- 

 cess extending inward. It is rather short and terminally 

 rounded. This process is present also in Ancistrona gig-as. 

 The outer posterior angle is truncated, and at its inner 

 corner, projecting from the ventral surface, is an articu- 

 lating condyle. This is some distance from the outer 

 corner, and to the latter is attached the extensor muscle. 

 The condyle projects backward and a little outward, and 

 fits into a socket of the head. Dorsal to this on the head 



