554 
AV. F. rUFCFLL. 
type found, accordiug to Lamy, in about half of the total 
number of genera examined, consists of four simple tracheal 
trunks united at base, as in text-fig. 21. It is known from 
the embryology that the lateral trunks of this type were 
derived from the pulmonary sac or ante-chamber of a lung- 
book, and are, therefore, homologous with the lateral trunks 
Traolieal apparatus of Liiiypliia triangularis. Cl. (act. 5- 
caustic potash). Magn. 80. can. Canal of coniinunication 
between the tracheal trunks, hy'. Terminal chitinous filires 
T)y which the medial or tendinal trunks (ni. tr.) ai'e attached to 
the entochondrites. I. tr. Basal portion of lateral trunk. 
Pedicel of trachea, rd. Lateral supporting rod. .sp". 
Spiracle. 
in Filistata, — while the medial trunks represent meta- 
morphosed entapophyses (ectodermal tendons of muscles), 
and are, as Lamy (p. 172) has pointed out, homologous "with 
