468 CALIFORNIA ACADEMY OF SCIENCES. 



is light yellow and has a slightly roughened or granular 

 surface. The interior is filled with cells, and perhaps 

 may be glandular. The excretory ducts are thick-walled 

 and strengthened by circular threads, as is often the case 

 with the salivary ducts of * insects." 



Scudder in his note "on the structure of the head of 

 Atropos,'" in "Psyche," 1877, vol. ii, p. 49, gives a differ- 

 ent account of the fork, saying that "instead of forming 

 a single, simple, rodlike process, this inner lobe [ = fork] 

 is three or four times as long as has been presumed, and 

 is two-jointed, the apical point lying, when the organ is 

 at rest, beside the basal joint, which is attached to the 

 maxilla at the extreme base of the latter; the basal joint 

 is directed backward and lies almost directly beneath the 

 basal portion of the apical joint." Mr. Scudder believes 

 that the fork is without any doubt homologous with the 

 customary inner lobe, or lacinia of the maxilla. As will 

 be noted in the foregoing quotation from Burgess, this 

 author believes Scudder's account of the fork as a two- 

 segmented organ to be erroneous, and he inclines to the 

 belief that the fork is an independent organ, and not a 

 part of the maxilla. 



Comparison and Conclusions. 



But little special attention need be given to the com- 

 parison of the mouth-parts of the Mallophaga with those 

 of the Termitidas and Perlidre. The last named families 

 (or orders) show the simple Orthoptero-Neuropterous 



"*The salivary ducts in most insects open by distinct apertures into the 

 oesophagus; still, they unite into a common duct in many Diptera and 

 some Orthoptera (see Siebold, Anat. Invert.). Siebold excepts only Mantis 

 among the Orthoptera, but Blalta, Termes and the Acrydians, at least, 

 must be added. The occurrence of salivary glands confined within the 

 head is also unusual, but not without precedent." 



