406 Mr. Teuipletoii on cerfuin SpiUtm. 



The necessity of separating this genus from the preceding, to which it 

 is very closely allied, can admit of no doubt. In the first place, its form 

 is exceedingly dissimilar, as will be apparent from a comparison of their 

 profiles, that of Dysdera being very elongate and cylindric, this short 

 and globose as in Theridion or Epeira, and the peduncle very far along its 

 inferior surface. The cephalothorax is also in this nearly rhomboidal, 

 the opposite sides being very nearly parallel, and the angle by which the 

 anterior recedes being very acute, while Dysdera is far from presenting 

 such a form, and the anterior superior angle is nearly a right one. The 

 eyes here also differ from those of every other genus, the large ones in the 

 centre and the lateral pairs being all oval*: not however perfectly regular, 

 the inner edges of the larger being nearly straight and their breadth being 

 diminished disproportionately anteriorly ; the lateral ones are much more 

 nearly perfectly oval but they differ slightly anteriorly. In the palpi the 

 greatest discrepancy occurs, and I know of no other genus in which the 

 hairs are serrated. The parts of the mouth are also unlike Dysdera. 



When the Spider is examined alive its blood f is perfectly transparent, 



* Though these eyes assume this singular form, to suit perhaps the oeconomy 

 of the animal, it is obvious that the surface must be part of the same solid of 

 revolution, else distinct vision would not be practicable: this is a curious 

 circumstance, and leads to the enquiry of how the surface becomes modified in 

 the compound eyes of Lamia, Saperda, &.c. 



f I know no more beautiful and interesting object, than the circulation of 

 the blood in the Spider presents under the microscope. It is much more dis- 

 tinctly seen in Clubiona atrox than in any other species I have yet examined, 

 from the circumstance that the particles or globules of the blood are very 

 opaque and therefore more distinctly observable. To see the motion in the legs 

 the age of the specimen matters not, but if the entire circulation be the subject 

 of investigation it is better to take the young, the central dorsal macula alone 

 being then distinctly marked. The mode I pursue, and which I recommend 

 for the adoption of others, consists in placing the Spider under water between 

 two plates of glass with a ring or two of card interposed of sufficient thickness 

 to prevent its being much compressed: the animal is thus prevented from strug- 

 gling, and as sufficient air remains in and about the pulmonary sacs to afford 

 an adequate supply of oxygen to it, it does not seem to suffer from the confine- 

 ment in water. By throwing the light of the reflector up, the circulation of 



