THE RENAL ORGANS (nEPHEIDIa) OP PATELLA. 375 



papillae of Patella, in order to test the accuracy of the figure 

 which Speiigel has given of their structure.' There is little 

 doubt that part of each of these papillae consists of a sensory organ 

 homologous with that which exists on the attachment of the 

 gill in Haliotis. A nerve from the visceral commissure can be 

 traced up to each papilla, as Spengel describes it, and in sec- 

 tions a nervous ganglion is seen beneath the epithelium, as in 

 his figure. Besides this ganglion there is to be seen in the 

 sections a cellular structure, oval in shape, surrounded by con- 

 nective tissue, and divided by trabeculse into compartments of 

 various size. This may be the branchial rudiment, but it lies 

 beneath the epithelium, and is not a special development 

 of it. 



^ " Die Geruclisorgane, etc., der Mollusken," ' Z. f. w. Z.,' Bd. xxxv. 



