Body iSpaces of Ihla Qtutdrivalvis. 229 



figures the organ (H)asaii "organ of unknown function," with no 

 communication with cavity (A). In my preparations, of Ibla this 

 organ opens without doubt into the space (A). From the nature 

 of the cells composing the walls, i.e., granular irregular cells, 

 I conclude that the organ is glandular and probably excretory 

 in function. Hoek also regards the gi'oup of cells lining the 

 entrance of the body cavity into the duct, as a segmental organ, 

 and believes it to be excretory in function. He tigm-es this as 

 composed of more than one layer of cells, and, though a doubt is 

 expressed, believes this to be the case. Further, he distinctly 

 states and shows in his figui'es that the cuticle does not continue 

 over these cells; but ends further up the duct. In my sections, 

 after careful examination, I have found no trace of more than 

 one layer of cubical cells, and in more than one case I have dis- 

 tinctly seen the cuticle passing over these cells and ending, 

 as stated above, at their junction with the flattened epithelial 

 cells lining the cavity (A). 



Gruvel [5] regards these cells as " mere annexes" to the main 

 apparatus, and from the above description it will be seen that 

 this is apparently the case here, as presumably no excretion 

 could take place from theui through the chitinous cuticle. They 

 ai'e very distinctly marked and prominent in all sections, but 

 what their function is it is impossible to say. 



Comparing these organs with structures present in other 

 forms, there appears to be little doubt that they fall into the 

 same category as the coxal glands of Limidus [Gulland, 11], the 

 shell glands of Crustacea which open in the same pnsition, viz., 

 at the base of the second maxilla, and the glands of cei'tain 

 Decapod Crustacea [Weddon, 17]. 



BiBLIOCxRAPHY. 



1. Bruntz, L. — L'Excretion chez les Cirripkles C.R. Acad. 



Sci. Paris, t. 135, 1902, No. 22, p. 987. 



2. Darwin, C. — Monograph of the Cirripedia. Ray. Soc, 1851. 



3. Goodrich, E. S. — On the Coelom, Genital Ducts and Neph- 



ridia. Q.J.M.S., vol. xxxvii., 1894, p. 477. 



4. (h-uvel, A. — Sur rarmature buocale et une nouvelle glande 



digestive des Cirrhipedes. C.R. Acad. Sci. Paris, t. 117, 

 1893, No. 24, p. 858. 



