'§1 310. TUE ARACIIXOIDAE. 383 



arterial trunk. The anterior of these arteries very soon ramifies, and dis- 

 tributes blood to the feet, the pincers, the cheliceres, and to all the organs 

 in the cephalic extremity. Two of its branches, bending downwards, em- 

 brace the oesophagus, and then join in a large common vessel called the 

 8upra-spinal artery, which lies upon the ventral cord and accompanies it to 

 the caudal extremity, giving off, in its course, numerous lateral branches. '■*> 

 The posterior arterial trunk is distributed in like manner to the posterior 

 extremity, and gives off, right and left, numerous branches. The middle 

 chambers of the heart send off, each, laterally, shorter arteries, which are 

 distributed to the neighboring organs. Beside these arteries of the muscles 

 and viscera, these animals have, also, a special Visceral artery, arising from 

 the anterior arterial trunk before it divides into the two branches which 

 form the supra-spinal artery. The visceral artery runs backwards towards 

 the digestive tube, and sends branches to the liver. <'> The terminal rami- 

 fications of these various arteries are directly continuous, it is said, with a 

 venous system.**^' In this last may be noticed, especially, a Sub-spinal 

 vein, by which the blood is carried to the pulmonary sacs ; thence to be 

 borne to the heart by special vessels. These last open, probably, into a 

 sinus, from which the blood passes into the heart through lateral openings, 

 two of which exist in each of its chambers.! 



4 This supra-spinal artery had been seen, it cisely this point, and has not distinctly indicated it 



would appear, by MuUer (loc. cit. p. 62, Taf. I. in his plates otherwise so beautiful, I demur admit- 



fig. 5, r. r.), but he took it for a ligament. ting that, with the Scorpionidae, the arteries pass 



3 According to Newport, this visceral artery, directly into the veins, and therefore, that these 



which is simple with AndToctonus, is divided into animals have a system of capillary vessels. This 



two trunks with Buthus. direct communication between these two systems 



fi Newport speaks in his memou- of various an- does not e.xist with the other Arachnoidae, neither 



astomoses occurring between the arteries and veins with all the other Arthropoda in general.* 

 with Scorpio. But, as he nowhere describes pre- 



* [ §. 310, note 6.] In regard to the question of pulraono-cardiac vessels^ wholly analogous to those 



capillaries with the Scorpionidae, a remark of we have described with the Araneae." — Ed. 



Blanchard (loc. cit.) may be given. He says, "I f [ § 310, end.] For further details on the cir- 



have proved with an enth-e certainty that the blood culatory system of the Arachnoidae, see the memoir 



is distributed in all the cavities of the body, as with quoted above of Blanchard. This naturalist has 



all the Articulata, and that it is conveyed to the sought to extend his doctrine of the peritrachean 



lungs simply by means of the lacimae. Most of the circulation, to the different sections of the Arach- 



vessels which arise from the sides of several of the noidae. Ed. 



chambers of the heart have appeared to me to be 



