May, 1902] 



PSYCHE. 



341 



bifurcated and project through the ven- 

 tral wall of the mouth thus lying free' 

 and uncovered in the mouth cavity. 

 Although not observed in the other two 

 genera of Mallophaga dissected, it is not 

 at all certain that they are not present, 

 their extreme minuteness and delicacy 

 making their discovery a matter of diffi- 

 culty. (Figures of these "forks" are 

 given on jDlate LX, New Mallophaga, 

 II.) 



For the rest, the Mallophagous mouth 

 is of simple biting type with a consider- 

 able reduction of the maxillae, the ma.x- 

 illary palpi being wholly wanting. 



Thanks to Edward Burgess the anat- 

 omy of the mouth of the Psocidae has 

 been known since 1S78.* The unusual 

 features, long familiar to entomologists 

 as curious and unique structures, of the 

 Psocid mouth parts are the so-called 

 "forks" of the mouth and the so-called 

 "oesophageal bone " and paired " lingual 

 glands" of the pharynx. Burgess's 

 description of one of the Psocid forks is 

 as follows. "This is a slender, more or 

 less curved chitinous rod with a forked 

 bifid tip, and two or three times as long 

 as the outer lobe. The distal portion 

 of the fork, about one-third or less of its 

 length, projects through the lining mem- 

 brane of the mouth. At this point the 

 fork is stoutest, and from it, it tapers to 

 either end, the outer portion being stout- 

 er than the inner. The membrane 

 where it is united with the fork is deli- 



*The anatomy of the head and the structure of the maxillae 

 in the Psocidae. Proc. Bost. Soc. Nat. Hist., 1878, Vol. 

 XIX, p. 291, pi. Vlll. 



cate and elastic, thus permitting the fork 

 to be projected forward or drawn back 

 at will. Within the head the fork is 

 held in position by muscles inserted on 

 its base, which unite it with the lobe and 

 .stripes of the maxilla, and by a ligament 

 which runs backward to the top of the 

 head." (Figures of the "forks" are 

 given in Burgess's paper, and copied in 

 plate LXIV of New Mallophaga, II.) 



I have simply to add that the Psocid 

 "forks" are in structure, position and 

 attachments practically identical with the 

 Mallophagous " forks," and whether Bur- 

 gess's view that the forks are new and 

 independent mouthparts, or .Scudder's 

 view that they are the modified maxillar 

 laciniae, be true, the Mallophagous forks 

 can readily be homologized with them, 

 for the Mallophagous maxillae have but 

 one terminal lobe and would be not at 

 all sorry to find in the forks their lost 

 laciniae ! 



Burgess's description of the " oesopha- 

 geal bone " of the Psocidae is as follows : 

 "Below the opening of the oesophagus 

 lies a bone which may be fancifully lik- 

 ened to a lady's bonnet upside down ; 

 the high front lies along the oral cavity 

 at about half way up ; two narrow exten- 

 sions, representing the bonnet strings, 

 run forward and upward, embracing the 

 oesophagous. The great bundles of 

 short muscles filling the large vaulted 

 clypeus 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. 



