OF WASHINGTON. 179 
of certain parts or organs, the family Filistatidce having four external 
stigmata, the posterior pair, however, aborted, showing also their affinity 
by the shape of the cephalothorax, by the stoutness of the legs, and the 
pubescence and color. Dysdertdce, belonging also to this group, possess 
also four external stigmata, but the posterior pair lead not to lamellar, but 
to common tubular tracheae ; they also have the mandibular claws inserted 
much as in the four-lungers ; that is, nearly vertical, instead of horizontal, 
as is the case of all other Dipneumonic spiders. 
Without these exceptions or transition-forms the two sub-orders seemed 
to be well separated, to be two natural groups, well defined in their struc- 
tural characters. They seemed so until Hypochilus was discovered.* 
Hypochilus is a Tetrapneumonic spider as well as a Dipneumonic one, 
for it has four lung-sacs, the vertical insertion of the mandibular claws, 
and the form and position of the labium proper to the former sub-order 
(the labium at least of some of the Territclarice), while it corresponds 
in the following characters with the two-lungers, especially with those ex- 
pressed in the above-mentioned group of transition forms. 
With the Filistatidce it has the cribellum and calamistrum and the ar- 
rangement of the eight eyes, and with the Dysdertdce the insertion of the 
mandibular claws, the four external stigmata, and the form of the male 
palpus; but it is also closely related to the Scytodidce, not only by some 
external features, but (as Prof. Bertkau, of Bonn, informs me) by 
anatomical homologies, and even with the Pholcidce with these princi- 
pally by the extremely long and slender legs, the shape of the body, and 
the similarity in the arrangement of the eyes. 
The Dysdertdce and Ftlistattdeeh&vt already by our arachnologists been 
placed at the end of the line of Dipneumonic families, opposite the Tctra- 
pnettmones, and Prof. Simon, of France, has added to this group the Scy- 
todidce (sub-order Gnaphosce). Now comes Hypochilus, standing directly 
in the gap that separates the two sub orders, leaning on one side upon the 
Filistatidce, on the other on Territelarice, connecting thus both divisions 
and obliterating their differentiating characters. 
The line of families would now, according to the order of their natural 
development, be formed as follows : 
Liphistatidce, Theraphosidce, Katadysidce <'?), Hypochilidce, Filistatidce, 
Dysderidce, Scytodidce, Pholcidce, Drassidce, and so forth, to the Epeiridce 
as the most highly developed family. 
Prof. Bertkau propo%ed, in 1882, a new classification, and divided the 
order Aranece into two sub-orders, according to the presence or absence 
of those peculiar organs, the cribellum and calamistrum. 
The Cribellata are those provided with these organs. This sub-order, 
however, contains the most heterogeneous families in spite of the great en- 
deavor the author made to demonstrate a certain natural relationship ex- 
isting between them. For Prof. Bertkau now to arrange matters with 
See my previous article on this interesting spider, pp. 166-167. 
