W. C. M'INTOSH ON VALENCINIA ARMANDI. 81 



layer of the body-wall is seen at d; vs, vs, the two dorsal accessory vascular channels between the 

 proboscidian sheath and the longitudinal muscular coat, x 90 diam. 



Fig. 5. Section through the anterior oesophageal region, showing the intraproboscidian vessel, va. The 

 proboscis, A, has been cut obliquely. The dorsal accessory vascular channels, vs, are very 

 distinct. The cutaneous basis-layer, b, shows traces of the separated series of longitudinal fibres, 

 but they are insignificant. At os is a slight inflection of the inner circular coat, indicating the 

 point of separation of the thin layer still representing the proboscidian sheath, x 90 diam. 



Fig. 6. Section through the internal circular muscular layer, os, in its complete condition, x 90 diam. 



Fig. 7. Transverse section behind the oesophageal region, and after the disappearance of the special inner 

 circular muscular layer (os, fig. 6) . The great development of the longitudinal muscular layer of 

 the body is apparent, as well as the regularity of its arrangement ; ol, inner (longitudinal) fibres 

 of the proboscidian sheath; oc, outer (circular) of the same, x 90 diam. 



Fig. 8. Section about one fifth of an inch from the tip of the tail, somewhat flattened by compression. The 

 proboscidian sheath (ao) is now very minute. The great longitudinal muscular layer (d) 

 presents no regular arrangement of its fasciculi ; and the lateral nerve-cord has almost reached 

 the circular coat (c) exteriorly. The area on each side of the now attenuated alimentary 

 canal is filled up by a translucent fibrous stroma, which in this preparation has been much 

 stretched, especially on the left side, x 90 diam. 



Fig. 9. Portion of the body- wall towards the middle of V. Armandi, from the great lateral vessel outwards, 

 showing the arrangement of the muscular fasciculi of the longitudinal layer, x 350 diam. 



Fig. 10. Section of a similar portion in Valencinia lineiformis. The great thickness of the basis-layer is 

 conspicuous. The arrangement of the longitudinal muscular fasciculi also contrasts with the 

 former, x 350 diam. 



