NEW MALLOPHAGA. 461 



around it, and attach by their ends to the dorsal wall of 

 the head. Opening into the median groove from its ven- 

 tral side is a small duct, which, followed to its source, is 

 seen to come from the union of a pair of ducts, each one 

 of which comes from an oval gland lying ventral to the 

 sclerite, and fitting into a concavity on the anterior end of 

 a weakly chitiriized, pedicle-like structure, which projects 

 backward and is attached by a foot-shaped expansion to 

 a large, strong muscle. This sclerite, which I call the 

 "oesophageal sclerite," shows distinctly through the dorsal 

 and ventral walls of the head, so that it is usually a con- 

 spicuous feature in the markings of the head, appearing 

 as a V- or U-shaped mark with thickened sides (see this 

 mark in the various figures illustrating the systematic part 

 of this paper). It is this sclerite which has been called 

 in the monographs of the European writers the labium, 

 and in my "New Mallophaga, I," I have constantly re- 

 ferred to it by the same name. It is this sclerite, too, 

 undoubtedly, which is the subject of Melnikoff's refer- 

 ences, in his embryological memoir, to a sucking appar- 

 atus. Grosse refers to this sclerite as the Schlundskelett, 

 and describes it, briefly, in Tctraofithalmus chilensis 

 (— Menojion titan) and Goniodes dissimilis. He found 

 also a chitin thickening of the dorsal wall of the pharynx, 

 immediately above the ventral sclerite. 



The mouth-parts of the Mallophaga are distinctly fitted 

 for biting; there are no mouth structures which lend any 

 probability to the old theory that the Mallophaga took food 

 by sucking. The peculiar pharyngeal structures, while 

 not yet understood in point of function, are not at all of 

 a character to suggest anything like a sucking function. 

 Grosse comes to no definite conclusion regarding the 

 function of these oesophageal sclerites, but he says: " Ich 

 schliesse aus seinem Bau, dass derselbe nichtzumSaugen, 



