224 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



sections beyond ; while the central mass is continued for 

 twenty sections more. 



The section figured (PL XIV., fig. 1) shows the anterior 

 pair of cerata (c 1 ), on the point of being separated off from 

 the body, while the second pair are not yet distinguishable 

 in any way. The liver (Z) is here seen as I have described, 

 with a central mass and two lateral smaller masses, and 

 the ventricle of the heart (v) is shown lying in the peri- 

 cardial cavity (p c). 



Figure 2, is drawn from a section fifteen higher in the 

 series than fig. 1. Here the anterior cerata are quite 

 distinct, and the posterior (c") are showing as distinct 

 prominences. The lateral processes of the liver (I') seen 

 in fig. 1, have now disappeared, and the much reduced 

 central mass remains. The coelomic cavity (cor) is also 

 much reduced, as the sections are now at a level at which 

 the mesodermal tissue of the dorsal body wall is appearing. 

 The distance of the liver mass from the place where the 

 cerata arise is very noticeable. 



Figure 3 is a section thirty higher in the series than 

 fig. 2. Here the second pair of cerata (c") have now 

 become almost entirely separated off, although a slight 

 attachment still persists in one. The liver has entirely 

 disappeared some twenty sections before, but the second 

 pair of cerata have not yet become quite distinct even here. 

 The first pair of cerata are here (fig. 3) cut, among the 

 smaller terminal branches. 



The minute examination of these sections of cerata, 

 whether taken before they are completely separated off 

 from the body and only showing as prominences at the 

 sides, or whether taken so as to cut through their base 

 just after separation, or whether sections of the terminal 

 twigs only, does not reveal any tissue that could possibly 

 be mistaken for liver. 



