book lung

Sternites: densely granulose throughout; sternites VI-VII with paired paramedian and lateral carinae, incomplete and granulose; booklung spiracles short and oval.

Most commonly, these ridges occur on the chelicerae (externally), and are rubbed by the palps; on the booklung covers, rubbed by the fourth legs; or on the coxae of the first legs rubbed by a peg on the second trochanters (e.g.

Ventral view: labium and maxillae yellowish brown, sternum and coxae brown, abdomen black, except for area above epigastric scutum and both posterior booklungs which are light brown.

Spiders in the Family Theraphosidae are distinguished from other spiders by the presence of two pair of booklungs; cheliceral fangs open paraxial; maxillae and labial cuspules present; distinct lobe on the anterior maxillae; two pairs of spinnerets; posterior lateral spinnerets are digitiform (finger-like); eight eyes in two close rectangular rows on a small anterior tubercle on the carapace; the legs and body are hirsute (hairy) and the tarsi (feet) are scopulated (padded) with retractable claw tufts (Raven, 1985).

Breathing, or gas exchange, takes place in folded, accordion-pleated, tissue called booklungs. Air enters and exits through the ventral side of the abdomen directly into the booklungs, where respiration occurs.