in the Spiders of the Genus Lycosa. 25 



cuna giving origin to ten lateral or transverse channels arranged 

 in pairs and starting from the median channel at more and more 

 open angles in proportion as they approach the anterior margin 

 of the animal. At the point of junction with each lateral channel 

 the median channel undergoes an enlargement_, from the bottom 

 of which blood-corpuscles are seen emerging from the deeper 

 parts. These corpuscles continue their course to right and left 

 in the lateral channels^ or forward in the median one as far as 

 the lower lip, where they also throw themselves into lateral 

 channels. Those corpuscles only which emerge from that enlarge- 

 ment of the median channel corresponding to the origin of the 

 hindmost pair of lateral channels, continue their course in great 

 part from before backwards in the posterior part of the median 

 channel. They then traverse the abdominal peduncle, and throw 

 themselves into the sinus of the base of the abdomen. 



The blood which passes from the median into the lateral 

 channels reaches the sides of the cephalothorax, where it unites 

 with the currents returning from the legs in a subcutaneous 

 lacuna occupying the whole lateral margin of the cephalothorax. 

 In this lacuna the blood moves from before backwards; it 

 arrives at the abdominal peduncle, where it empties itself, with 

 the blood of the median channel, into the sinus of the base of 

 the abdomen. 



The lateral channels of the sternum do not, however, receive 

 blood only from the median channel ; at certain distances they 

 themselves present enlarged spaces, from the bottom of which 

 corpuscles are seen emerging, which come from still more deeply 

 seated regions. These corpuscles continue their course with the 

 blood coming from the median channel. 



The enlarged spaces to which I have just adverted in the 

 median and lateral channels establish a communication between 

 these channels and more deeply seated lacunse. The latter exist 

 between the muscular masses which are bounded at the surface 

 by the channels themselves ; this is so true, that the interstices 

 of communication are in part temporary. They are sometimes 

 seen to close whilst others open beside them. In all cases their 

 diameter varies continually, according to the movements of the 

 animal. These lacunse receive their blood from the sternal 

 arteries, which open into them without any ramification. 



The cephalothorax, examined from its dorsal surface, presents 

 a less complex venous system. The eyes are bathed posteriorly 

 by a lacuna which receives its blood from the ophthalmic arte- 

 ries and conducts it into the lacunse of the sides of the thorax 

 already mentioned. Besides these, a subcutaneous channel (the 

 median tergal channel) conveys the blood in a direct line to the 

 abdominal peduncle. This channel receives its blood in part 



