ItESriBATOBY ORGANS IN ARANE^. 
63 
was (’95, pp. 398, 399) : “ The homologon of the lung is 
represented in the latter groups [Agelenidm, etc.] by the 
lateral pair of tracheal trunks, but in the Attidse by a mere 
rudiment in the form of a short lateral process on each side 
at the base of the two large trunks.”^ There was, therefore, 
no need to have differed from me as to the presence of the 
homologa of the lungs. 
The Agelena-type of tracheae and its development. — It was 
shown long ago, first by v. Siebold (’48) and later by 
Bertkau (’72, ’78) and Lamy (:02), that many families of 
Dipneumonous spiders (about half of the genera examined, 
according to Lamy, p. 227) possess a much simpler tracheal 
system than that which occurs in the Attidae. This simpli- 
fied system^ consists of four long trunks united behind at the 
base, as in fig. 21, but without any of the fine secondary 
tubules found in the Attidae. 
Such tracheae occur in the Agelenidae, Clubionidee, 
Drassidae, Argiopidae, Lycosidae, Theridiidae, etc., and 
their relation to the Attus-type of trachea may be at once 
seen by comparing fig. 21 (Tegenaria) with fig. 29 (young 
Attus). Here the tendinal trunks [m. tr.) in the latter are 
obviously equivalent to the medial pair of trunks in Tege- 
naria, while the lateral branch {l.tr.) on each side in Attus 
is represented by the pair of lateral trunks, which, therefore, 
are serially homologous Avith the dorsal proliferation of the 
embryonal pulmonary sac. 
That this is really the case may also be easily shown from 
the embryological material of Agelena labyrinthica in 
my possession. Shortly before the hatching of the embryo 
and after the completion of the reversion in this species, the 
pair of tracheal plates have very much the same form as in 
tracliees des Attidae, aux(juelles il donne une origine entiHement 
entapophysaire, ne me semble pas acceptable.” 
‘ On p. 248 Lamy cAirioiisly enough correctly quotes this statement. 
® Literature : v. Siebold (’48, jj. 535), Leydig ('55, p. 460), Bertkau 
('72. '78), Schimkevvitsch ('84), W. AVagner ('88, figs. 26, 67, and 68), 
Vogt ('89, p. 226), Lamy (:00, :01, :02). 
