488 W. i?. Coe — Anat07ny of Cerehratulns lacteua. 



boscis-sheath is innervated by nerve-fibres which pass from the dorsal 

 nerve through the two inner layers of the body-musculature. 



The Proboscis. 



The proboscis (Plate XI, fig. 2 ; Plate XII, figs. 1, 2, p ; figs. 11, 

 12, 13) consists of a tube with thick muscular walls which are attached 

 anteriorly to the muscles of the head just in front of the brain (Plate 

 XI, fig. 2 ; Plate XII, figs. 1, 2). Although often nearly as long as the 

 entire animal, it usually lies coiled up in the oesophagal region and 

 reaches only a short distance further back. In the Enopla and in 

 many of the Anopla this organ has its blind posterior end attached 

 by a slender fibrous ribbon to the dorsal wall of the proboscis-sheath. 

 This attachment is readily observed in the living worm or in micro- 

 scopic sections. In this species, although I have examined a great 

 number of individuals with reference to this point, I have been unable 

 to find any such attachment. In all cases the proboscis lay coiled up 

 within its sheath, and its smooth, rounded extremity (Plate XII, fig. 

 10) showed no evidence of having had any connection with the pro- 

 boscis-sheath. 



The wall of the proboscis shows a striking similarity to the body- 

 wall both in the number and in the arrangement of the constituent 

 layers. A comparison of the diagrams on Plate XII, figures 5 and 

 6, will serve as an illustration of this close resemblance. Of course 

 the curvature of the layers is different; but this would not be the case 

 when the proboscis is extruded. In the body-wall, fig. 5, we find an 

 outer epithelium (e) ; an outer longitudinal muscular layer (/m') ; a 

 nerve-plexus {iip) ; a circular muscular layer [cni) ; and an inner 

 longitudinal muscular layer (lri%). Likewise the proboscis, fig. 6, is 

 made up of an inner epithelium (e) ; an inner longitudinal muscular 

 layer {In-i) ; a nerve-plexus {i%p) ; an inner circular muscular layer 

 (cm) ; an outer longitudinal muscular layer (l-ni!) ; and an outer cir- 

 cular muscular layer {om'), besides a delicate endothelium {e?i) 

 bathed in the fluid of the rhynchocoelom. 



The inner epithelial layer (Plate XII, figs. 11, 12, 13 e) is thrown 

 up into large, circular folds which are more or less broken up into 

 rounded papillae by irregular longitudinal folds. The epithelium is 

 directly continuous with that of the rhynchodseum, and is made up of 

 long columnar cells (Plate XII, fig. 3) which are mostly filled with 

 glandular secretion. The cells (a) which clothe the immediate lumen 

 of the proboscis have, in many cases, in their free, outer borders a 

 cluster of slender, rod-like bodies (ro) resembling the rhabdites of the 



