The its muscular coat; g, g, the heart is of the usual Arthro lateral teeth, which when podous type, lying in a more or in use are brought in conless well-defined pericardial blood tact with the sides of the sinus, with which it communi median tooth m; c, c, the cates by valvular openings or muscular coat.
The walls of the pericardium are also excretory in parts, these parts forming the pericardial glands.
The floor of the pericardial bb, Cut remnant of the auricle.
In Scutigera there are seven unpaired dorsal stigmata, each leading into a sac whence a number of air-holding tubes project into the pericardial blood-sinus.
- Diagram to show the gradual formation of the Arthropod pericardial blood-sinus and "ostiate " heart by the swelling up (phleboedesis) of the veins entering the dorsal vessel or heart of a Chaetopod-like ancestor.