114 S. GOTO. 



after all not clear to me what the author meiins wlieii he speaks of a 

 " cuticle " containing nuclei and of a layer of finely granular, or, as he 

 says, homogeneous substance lining a ca\'ity as being of a connective 

 tissue nature. Comparative considerations seem to me to compel us to 

 regard the wall of the' ootyp of Monocotijle and Calicotijle as consisting 

 of a true epithelium ; only in the case of Tristomwn the cell-boundaries 

 have completely, and in that of Oncliocotijle partly, disappeared. 



In Tristomuin the mesenchyniii around the ootyp presents an 

 appearance very dilFerent from that of the rest. Where' the 

 general mesenchyma consists of a fibrous connective tissue, the 

 reticulum is always much looser around the ootyp than in the other 

 parts. In Tvint. sinuatwn in which, as already described, the mesen- 

 ch3'ma consists of a syncytium, the part around the ootyp contains 

 numerous ca\'ities separated from each other by a thin layer 

 of the syncytium (PI. XXIT, fig. 4). This loose portion of the 

 mesenchyma is, in all the species, surrounded by a layer of muscular 

 fibres, which ai'e of two sorts, those which run parallel to the length 

 of the ootyp and tliose that run in a dorso-ventral direction. The 

 latter fibres are no other than the dorso-ventral fibres of the body. 

 The two sets of fibres are also present aroimd the uterus, and therefore 

 the farther course of the horizontiil fibres will be again treated of 

 under that head. They evidently serve by their contraction to drive 

 out the egg from the ootyp. 



Returning to the ootyp of Monocotijle and Calicotijle and consider- 

 ing the fippeai'ance and reaction towards colouring fluids of the cells 

 that constitute its wall, one is, I think, strongly tempted to sus- 

 pect their glandular nature. But as the shell-glands are present out- 

 side the ootyp, I can not conceise any purpose they might serve 

 in case of their being really glands. They are probably a simple lining 

 epithelium, of which, however, the character has undergone a certain 



