162 PEOFESSOB E. ELY LANKESTEK. 



of the ductless glands of Vertebrata. On the other hand, it is 

 possible (and more probable) that whilst their intercsecal 

 framework is developed from skeleto-trophic tissue, the lining 

 layer of cells of their glandular caeca is an oflFset either of the 

 epiblast or of the hypoblast (that is, either of the epidermal 

 cell-layer or of the enteric cell-layer). 



In any case, the occurrence of these glands in their charac- 

 teristic position, and with their characteristic corticated secre- 

 tory cells in Limulus on the one hand, and in Scorpio and 

 Mygale on the other, is one more argument in favour of the 

 classificatory association of Limulus with the Arachnida. 



