32 THOS. H. MONTGOMERY, 



tissue of the body epithelium. In T. catenulatum this tissue 

 is pigmented, but dififers from that of Stichostemma, inasmuch as the 

 pigment is not universally distributed in it, and also that the tissue 

 is less massively developed. The pigment is, namely, found only in 

 the cells of this tissue in certain regions, corresponding to the brown 

 mottlings of the living worm. This yellowish pigment occurs, either 

 in the form of scarcely visible granules, or as comparatively large, 

 homogeneous masses; and since both modes of distribution are found 

 in adjacent cells, neither mode is an outcome of the action of the 

 fixing fluid (Fig. 34). Further, in this species, in! contrast to T. vermi- 

 culum^ no pigment occurs in the supporting cells of the body 

 epithelium. 



IX. SticJiosfemnia eilhardi Montg. 



1) Branched connective tissue cells, with inter- 

 cellular substance. This tissue composes the basement membrane 

 of the body epithelium, the intermuscular elements in the body wall, 

 proboscis and its sheath, the layer outside of the intima of the blood 

 vessels and rhynchocoel; and that sheath (Figs. 39, 40 Mem) around 

 the intestine, lateral expansions of which enclose the nerve chords, 

 lateral vessels, and gonads (this sheath being equivalent to the 

 somato -\- splanchnopleura of Salensky, '84 ; cf. my remarks on these 

 layers in AmpMporus glutinosus). This tissue has thus the same 

 distribution, as in Amphiporus and Tetrastemma ; for a description 

 of the basal membrane of the body epithelium, which is structurally 

 similar to that of the genera just mentioned, compare my previous 

 paper ('95 a). Between the intestinal diverticula, this tissue forms 

 frontally situated, sheet-like expansions, comparable to septa. 



The gonads and the genital cells are derivatives of the connec- 

 tive tissue sheath, between the intestine and the body wall (Fig. 39) 

 as in Amphiporus ; but in contrast to the latter, the testicular as well 

 as ovarial efferent ducts are always situated above the nerve chord. 



2) Mesenchym tissue. Only in immature individuals (males 

 and young hermaphrodites), we find a thin split between the longi- 

 tudinal muscle layer and that sheath of connective tissue enveloping 

 the intestine (Figs. 39, 40 B.C); in more mature individuals, charac- 

 terised by ova, this split becomes obliterated. This cavity is trans- 

 versed by the dorso-ventral musculature, and by fibres from the 

 connective tissue sheath. This space is, in life, probably filled with 

 a thin fluid, since in preparations it offers no evidences of structure. 



