(> DR. J. F. GEMMILL ON THE 



Area. Description of Current. 



Aboral wall of disc Centrifugal iuterradially, and for the most part 



radially as well, but sometimes, especially in 

 Asterias, centripetal or mixed along tlie 

 continuations of the epigastric cuelomic 

 pockets. 



Aboral gastric ligaments Aboralwards. 



Oral gastric ligaments Mixed, chiefly centrifugal. 



3 (b). Lining op Perivisceral Cavity : Splanchnopleure. 



Pharyngeal portion of stomach ... Aboralwards in all. 



Gastric portion of stomach Aboralwards in all. 



Pyloric sac Aboralwards in all. 



Stalks or radial Cfflca (except sur- Centrifugal in all. 

 faces looking into epigastric 

 ccelomic pockets). 



Surfaces of radial caeca looking In Asterias and Porania centripetal * : in 

 into epigastric cuelomic pockets. Solaster mixed centrifugal and centripetal. 



Oral edges of radial casca Centrifugal in all. 



Sides of radial caeca Aboralwards in all. 



Aboral edges of radial cpeca and Centrifugal in all. 

 outer aspects of epigastric 

 mesenteries. 



Rectal caeca Centrifugal with spiral currents and mixing, and 



in some cases a tendency towards circulation 

 in a dextral direction as viewed aborally. 



Region of separation between * Slight tendency towards circulation in a 

 stomachal and pyloric regions of dextral direction as viewed aborally. 



gastric cavity. 



Gonads and Polian vesicles In general from attacbed to free extremities, 



but sometimes spiral or mixed. 



General. — Here the primary fact is that the ciliation produces 

 constant and complete mixing of the ccelomic fluid in the interior 

 of the disc and arms. Great centripetal currents flow along the 

 in fere -lateral angles of the arms and, reaching the splanchno- 

 pleure of the gut-wall, are swept aboralwards and are next driven 

 centrifugal ly outwards towards the arm-tips by the cilia on the 

 aboral body-wall and on the radial and rectal ca?ca, There appeals 

 to be a certain amount of circular movement on the part of the 

 ccelomic fluid in the dextral or watch-hand direction as viewed 

 aborally. Continual changing of the fluid inside the gills also 

 occurs. 



4. Endodermal Lining. 



Area. Description of Current. 



Pharyngeal portion of gastric Aboralwards in all ; in Asterias a slight oral- 

 cavity, ward current could sometimes be made out 



in the middle line of one or other of tbe 

 interradii, particularly of the anal inter- 

 radius. 



* Currents somewhat variable. 



