1883.] NATURAL SCIENCES OP PHILADELPHIA. 237 



the left and posterior part of the pulmobi'anehial pouch, and 

 extends transversely and expands behind the auricle and the 

 ventricle. Its color is yellowish, and opens without doubt at the 

 side of the respirator}'- orifice."^ He says further on : " The peri- 

 cardial gland produces a very large amount of mucus, I have 

 never found calcareous granules in it ; these I have only found in 

 the thick part of the mantle, principally near the margin ; they 

 were very large, a little irregular and transparent."^ Although I 

 have diligentlj^ searched for the reticulated part described by G. 

 Yogt, I have been unable to find it. It appears to me that he 

 had reference to what I have called the sacular part of the kidney, 

 later to be considered, which lies close to the pericardium, the 

 walls of which have not a reticulated appearance, but are thrown 

 into longitudinal folds. C. Yogt regarded this part of the organ 

 as the lung, while Moquin-Tandon, on the other hand, called it the 

 pericardial gland. 



When the animal is laid upon its back, and the mantle and foot 

 separated, an S-shaped yellow body is seen through the thin walls 

 of the mantle. 



In A. fiuviatilis this organ lies in the left, and in A. lacustris 

 in the right lobe of the mantle ; this is the organ of excretion, or 

 the kidney. Were this organ to be dissected out and measured, 

 it would be found to be about twice the length of the animal to 

 which it belonged ; thus in an animal measuring 7*4 mm., the 

 kidney was found to measure 14*4 mm. 



In fig. 10 (PI. X) I have endeavored to give a diagramatical 

 drawing of the course of the kidney. To the largest part I have 

 given the name of the sacular portion ; it lies in contact with the 



^ L' orifice respiratoire est ti es petit et perce dans un epaississement de la 

 peu, un peu plus pale que la i-e.^te du tissue * * *. La glande pericar- 

 diale est accolee conime dans la plupart des Gastropodes, au coeur et a 

 I'oj-gaue de la respiration ; elle <'ccupe les parties glauches et posterieures 

 de la poclie pulmobranclie, et s'elend transversalement, en se renflent, 

 derriere I'oreillette et le ventricle. Sa coleur est jaunatre, s'ouvre sans 

 doute, a cote de I'orifice respiratoire. Recher. anat. pbysiol. s. I'Ancyle, 

 etc., p. 128. 



^ La glande pericardiale pi'oduit une assez grande quantite de mucus. 

 Je n'y ai jamais trouve de grains calcaires. J'en ai observe seulment 

 dans I'epaisseur du manteau particulierment vero sa marge ; ils etaient 

 assez gros, un peu irreguliers et transparent s. Recber. anat. pbysiol. s. 

 I'Ancyle, etc., p. 138. 



