182 Dr. T. Williams on the Mechanism of Aquatic 



able sera in the anatomical history of the Invertebrate animals*. 

 His researches are masterpieces of minute and difficult ana- 

 tomy ; they deserve, as they have received, the admiration of all 

 scientific men. The age of authority is gone by. Truth must 

 now be reverenced at her native shrine, and Mr. Newport must 

 submit to the criticism of his peers. Mr. Newport's anatomy is 

 exact, but his reasoning is unintelligibly contradictory. His 

 researches relate exclusively to the central parts of the circu- 

 lating system of the tracheary Articulata ; he has not attempted 

 to investigate the peripheric. This is a natural division of this 

 subject. Let these heads be discussed separately. 



Central Parts of the Circulatory System in the Myriapoda, 

 Insect a, and Arachnida. 



The researches of Baker, Carus, Wagner f, Lyonet %, Cuvier §, 

 Treviranusll, Latreille^, Straus -Durkheim**, Mr.Bpwerbanktt^ 

 TyrrelJI, Miiller§§, Hunter, Lord||l|, Newport!^, in con- 

 nexion with this subject, should be historically signalized ; they 

 deserve the reverence, but not the servile acceptance, of the sci- 

 entific scholar ; they involve a vast mass of laboriously acquired 

 knowledge ; they constitute the foundation whereon all future 

 additions must rest. 



The myi-iapodal ' circulation ' exists in its least complex form 

 in the lulidce. Of this family the Spirostrepti and Spiroboli re- 

 present the lowest genera. Mr. Newport has proved that the 

 chambers of the heart decrease in number as the articulate scale 

 is followed upwards from the lowxst Myriapod to the highest 

 Arachnid. This principle is not observed in the larva of all in- 

 sects. In several aquatic species, the great venous abdominal 

 currents may be followed most perfectly with the eye, and seen to 

 enter the dorsal vessel only at its posterior extremity, where alone 

 auricular orifices exist (PI. IX. fig. 4, b) . The dorsal vessel {a) of 



* On the nervous and circulatory systems, and on the existence of a 

 complete circulation of blood in vessels, in Myriapoda and Macrourous 

 Arachnida, Phil. Trans. 184^. Also Art. Insecia, Cyclop. Anat. and Phys. ; 

 and various papers in the ' Linnajan Transactions,' by George Newport, Esq. 



t Isis, 1832. :J: Traite Anatomique de la Chenille, &c., 1760. 



§ Ije9ons d'Anat. Comp. 



II Die Arachniden, 1812; and also his Vermischte Schriften Anato- 

 mischen und Physiologischen Inhalts. Gottingen, 1816 (Die Spinne), p. 5. 



^ Coiu-s d'Entomologie, &c., Paris, 1831. 



** Considerations generales sur I'Anat. Comp. des An. Art., 4to, Paris, 

 1828. 



ft Entom. Mag. vol. i. April 1833. 



XX Proceedings of the Royal Society, 1835. 



§§ Nova Acta Nat. xii. 2. 



111! Medical Gazette, 1838. Tf Op. cit. 



