Ada Acad. Natura Curiosa Bounce. 593 



Bungarus, &c. ; the second, truly venomous, as Trigonocephalus, 

 Cophias, Vipera, Pelias, Crotulus, &c. ; the third, water-serpents, 

 with the exception of Chersydrus, which is innoxious, and a true 

 Acrochordus. The species of the first, family possess the venom 

 apparatus like the rest; the perforated tooth, however, has not 

 merely an aperture above and below, but is also open along the 

 whole length of its front edge, and, consequently, therein approxi- 

 mates to those with the fissured posterior tooth. 



In the same manner that the superior maxilla is shortened in those 

 species where there is a perforated posterior tooth, so is it also in 

 the Colubrine family, but is still longer than in the Viperine genera, 

 where the ranges of un-perforated teeth disappear, the venom- fangs 

 alone remaining. The external pterygoid bone is elongated in the 

 same proportion as the superior maxilla is shortened, and the mobi- 

 lity of the latter is obviously in the same degree increased, inasmuch 

 as it is attached to the extremity of a lever of greater length. 



The facts above stated may serve to explain the discrepancies in 

 the statements of the consequences of the wounds inflicted by those 

 serpents which have the posterior tooth perforated. When the 

 latter penetrates the wound, fatal effects may ensue ; whilst, on the 

 contrary, when the anterior teeth only act, the injury will not have 

 more serious results than those of the bite of an ordinary Coluber. 



Is it allowable to suppose that the ancients were acquainted with 

 a serpent of this kind, and that they therefore distinguished their 

 , as one, the bite of which caused extreme thirst? 



Anatomy of the Nervous and Vascular Systems of Nais diaphatia. 

 By Dr. Gruithuisen. 



THE head of this animal is characterized by a set of muscular fibres 

 radiating around the pharynx ; by means of them that cavity is di- 

 lated, and when the prey (infusoria) of the animal is drawn into it, 

 which is done with the rapidity of lightning, they close the mouth, 

 and force the food onwards towards the stomach. 



The alimentary canal presents alternate expansions and contrac- 

 tions : the first cavity (stomach) is surrounded by little glands in 

 double rows, the remaining part of the canal is beset with larger 

 glands in single rows. These glands separate the chyle from the 

 contents of the intestine, and convey it into the space between that 

 canal and the general muscular stratum placed beneath the skin. 



The nervous system begins as a large knotted cord surrounding 

 the pharynx, and continued inferiorly as a solid cord accompanying 

 the oesophagus, and so broad as to project beyond the lateral edges 

 of that canal. Two nerves proceed from the cerebral ganglion to 

 the extremity of the mouth. The principal nervous cord is irregu- 

 larly studded with ganglia, and has an imperfect line of division in 

 the longitudinal direction. It gives off numerous branches to the 

 intestinal canal, to the arteries, and veins, and to the muscles of the 

 integuments and bristles, or sett. 



