150 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



canals into the lacunar system of the body-wall. 

 The scale applies to both figures. 



Plate XXXVII. 



Fig. 1. Horizontal section of the madreporic interradius of 

 a young Asterias ruhens. 



Fig. 2. A similar section from an older specimen. 



Fig. 3. Part (peripheral) of a tranverse section of the cen- 

 tral plexus of an adult Crihrella sanguinolenta. 



Fig. 4. A section similar to figs. 1 and 2 showing the 

 relation of the gastric haemal strands to the 

 central plexus and the gut. 



Plate XXXVIII. 



Fig. 1. Diagram of the central portions of the water- 

 vascular and nervous systems of Asterias ruhens, 

 constructed from thirteen consecutive horizontal 

 sections of the disc. 



Fig. 2. Diagram of the central portions of the water- 

 vascular and hiemal systems of Asterias ruhens, 

 constructed from several series of sections. Com- 

 pare with Fig. 1, Plate XXXIX. 



Fig. 3. Vertical section through the peristome of Asterias 

 ruhens. The scale applies to figs. 1 and 3. 



Plate XXXIX. 



Fig. 1. Diagram of the central portions of the water- 

 vascular and haemal systems of Asterias ruhens, 

 constructed from ten consecutive sagittal sections 

 through the madreporic interradius. 



Fig. 2. Transverse section of the vertical septum which 

 divides the radial perihaemal canals, showing four 

 haemal lacunae. The dotted line in the upper 

 ones represents coagulum. 



Fig. 3. Longitudinal section of the oral end of the cen- 

 tral plexus of Asterias ruhens. 



