THE THYLOGENY OE THE TEACHE.E IN ARANE.H. 535 
Dysderina. Neither o£ these authors, however, observed 
the anterior ending of the ceplialothoracic trunks, but quite 
correctly supposed them to eud, as in the Dysderidm, in a 
bundle of tubules. In Calculus bicolor these trunks are 
short and very much as in text-fig. 6. They do not enter the 
abdominal pedicel, but break up at the anterior end into a 
dense cluster of fine tubules, which then pass through the 
pedicel into the cephalothorax. 'J'he short posterior branch, 
fii’st found in this family by Lamy, is also present, and 
corresponds exactly to the similar branch in the Dysderidae. 
The anastomosing ends of the internal spines form a simple 
network, like that in Harpactes, but in the forms examined 
by Bertkau and Lamy they are said to form a spiral thread. 
The cavities of the two tracheal trunks are directly connected 
by a spinous canal of communication (fig. 1, can.), enclosed 
within the iutertracheal fold [tr. fd.). As in the Bys- 
d e r i d a3, the tracheal trunks and their branches 
are to be considered as entirely homologous with 
lung- books. 
Another important point of resemblance to the Dys- 
deridte is the presence in the female of a single median 
receptaculum seminis, pointed out by Bertkau (’78), who 
observed that such a receptaculum is not found in any other 
family of spiders besides these two (p. 374). In Calculus 
bicolor the receptaculum forms an elongate, narrow, curved, 
median pouch (fig. 2, r. s.), placed horizontally with the 
concavity of the curvature upwards, and opening into the 
anterior wall of the epigastric fold {ep. fd.). From the under 
side of the pouch a large vertical keel {Ic.) hangs downwaids, 
reaching to the body hypodermis. Fach side of this keel 
serves for the attachment of a powerful muscle (/a. 38), which 
runs obliquely backwards and outwards to the anterior surface 
of the entapophysis of the epigastric fold (tig. 1). There is 
also a median muscle {ui. 4Uj running’ from the under side of 
the pouch along the posterior edge of the keel to the ventral 
body integument. In Harpactes Hombergi I found a 
very similar receptaculum, provided with a similar remark- 
