1877.] 79 [Scudder. 



between investing tunics, lies a closely coiled spiral thread; and out- 

 side of and enveloping which is the peritracheal vessel, whose outer 

 walls are not limited by the extent of the tracheae proper, but ex- 

 tend beyond the spiral coil to form the second and distinct part of 

 the system, — namely, capillary tubes, penetrating every portion and 

 organ of the body, and terminating in a mesh-work of interlacing 

 branches. In other words, this portion of the circulatory system 

 consists of branching tubes, which enclose within all but their ulti- 

 mate ramifications the similarly branching tubes of the respiratory 

 system. The fluids, therefore, forced by the dorsal vessel into the 

 peritracheal cavities, become thoroughly aerated before passing into 

 the tissues of the body to perform their functions ; when they have 

 done their work they empty into the general cavity of the body, and 

 mingling with the fluids newly expressed from the alimentary canal, 

 join the general currents which, as first shown by Carus, appear to 

 set, in regular channels at the sides and floor of the body, often, 

 however, with no vascular boundaries, toward the hinder extremity 

 of the body, or toward the sides of the dorsal vessel, to enter again 

 the initial point of the circulation. 



General Meeting. February 21, 1877. 



The President, Mr. T. T. Bouve, in the chair. Twenty- 

 seven persons present. 



Mr. C. S. Minot read a paper on the Classification of the 

 Trematod worms, giving a particular account of the anat- 

 omy of Distoma crassicotte, parasitic on the European Sala- 

 mandra. 



Mr. S. H. Scudder made some remarks on the metamor- 

 phoses of insects. 



Mr. Charles W. Scudder was elected Treasurer. 



The thanks of the Society were voted to Mr. Gurdon 

 Saltonstall, for a valuable series of Corals from Nassau. 



PROCEEDINGS B. S. N. H. — VOL. XIX. 6 JULY, 1877. 



