74 W. C. M'INTOSH ON VALENCLNIA ARMANDI. 



Carinella, fibres from the elaborate muscular system of the snout pass from the trans- 

 verse bands into the cutaneous layer ; so that, with the arrangement of the basis-layer, the 

 tissue has a characteristic arborescent appearance. 



Underneath the basis-layer is a well-marked belt of circular muscular fibres. Towards 

 the tip of the snout these fibres are not developed as an external coat, probably because 

 the complex system of internal muscles, hereafter to be described, renders their presence 

 less necessary. Immediately behind the anterior border of the snout (fig. 1) a differen- 

 tiation of the cutaneous stroma occurs. At first, in front of the proboscidian aperture, 

 a single distinct transverse band appears, with numerous vascular meshes beneath it, 

 such probably representing the area of communication between the lateral trunks. Two 

 transverse muscular bands, however, as soon as the proboscidian canal is reached (fig. 2, 

 e & e'), pass from side to side, leaving a considerable space between them ; and this is 

 occupied by vertical bundles, which enclose various meshes, the chief being in the centre 

 for the proboscidian canal, while several smaller vascular spaces exist on each side. 

 Very shortly, however, as we proceed backward, greater differentiation occurs ; for the 

 transverse bands increase in strength, and numerous longitudinal muscular fibres appear 

 above and beneath their outer borders. A transverse section, therefore, in this region 

 (fig. 2) shows beneath the cutis (a) the pale and comparatively thin basis-layer (b). The 

 two great transverse muscular bands (e & e') pass right across, forming a kind of ellipse, 

 each spreading out so as almost to meet its fellow at the circumference on each side, and 

 perforated here and there by the vertical bands. Numerous vertical bands extend 

 from the superior and inferior borders of the ellipse to the circumference, often in an 

 arborescent manner, and become lost at the basis-layer. The spaces thus left between 

 the outer edge of the ellipse and the latter are filled with powerful bundles of longitudinal 

 muscular fibres (d). The area of the ellipse, again, presents the canal for the proboscis 

 (a o) in the centre, with its pale glandular lining internally, and externally its strong coat 

 of longitudinal muscular fibres. This canal is supported on each side by vertical mus- 

 cular bands, whose fibres, spreading out at each transverse muscle, pass to the circum- 

 ference above and beneath. Two bundles of fibres are especially conspicuous on each 

 side. Then come a great vascular space and a small one between it and the circumfer- 

 ence. Between these spaces and at the outer edge similar vertical bands of fibres occur, 

 with numerous longitudinal fasciculi. Along the inferior border of the superior trans- 

 verse muscle and the superior border of the inferior are many longitudinal bundles, form- 

 ing a somewhat regularly diminishing series towards the central line. Proceeding back- 

 ward, it is found that the chief changes in the great transverse bands are their diminu- 

 tion in length, increase in bulk, and more evident divergence at the extremities, so that 

 their lateral fibres almost decussate. The superior and inferior vertical bands are also 

 more boldly developed. There are still two vascular tubes on each side of the probosci- 

 dian canal, a larger and a smaller. By-and-by there is a tendency to further differentia- 

 tion in the proboscidian and in the vascular area, as shown by the greater development 

 of a lateral vertical band, composed internally of longitudinal, and externally of vertical 

 fibres. This becomes marked as soon as the anterior border of the ganglia and the turn- 

 ing over of the proboscidian sheath are reached, while only a single vascular channel is 



