466 CALIFORNIA ACADEMY OF SCIENCES. 



backward to the top of the head. Of these muscles one 

 is inserted on the base of the lobe; two others are in- 

 serted apparently within the stipes; by their contraction 

 the fork is thrown forward out of the mouth, or moved 

 about. The backward-running cord, which is double, is 

 apparently neither muscular nor the tendon of a muscle, 

 but simply an elastic ligament to draw the fork back, and 

 probably the membrane pierced by the fork aids in the 

 same movement. The fork is still further held in place 

 by the flexor muscles of the stipes and lobe which pass 

 behind it and serve to bind it down against the lobe. 



"In the maxilla we have recognized cardo, stipes, and 

 outer lobe, and one naturally asks if the fork is the homo- 

 logue of the inner lobe of the typical maxilla, or an inde- 

 pendent organ. At present I must incline to the latter 

 view, although some may regard the absence of anything 

 else to represent the inner lobe as sufficient evidence of 

 their homology. B,ut there is no articulation of any kind 

 between the fork and the outer lobe, and the peculiarity 

 of the muscular connections seem rather to favor the idea 

 that the fork may represent an independent organ. 



"The maxillae and mandibles occupy the lower half of 

 the large oral cavity which opens above into a thick-walled 

 oesophagus. Below the opening of the oesophagus lies a 

 bone which may be. fancifully likened to a lady's bonnet 

 upside down (plate lxiv, fig. 11 and oe. b. fig. 9); the 

 high front lies along the oral cavity at about half way up ; 

 two narrow extensions, representing the bonnet strings, 

 run forward and upward, embracing the oesophagus. 

 The great bundles of short muscles filling the large 

 vaulted clypeus (plate lxiv, fig. 9) are attached to the 

 ends of these strings, and by their contraction close the 

 oesophagus. Just below the 'front' a fine duct opens 

 which is the common duct of a pair of lingual glands, 



