68 ANATOMY OF THE ENOPLA. 



in the elongated reservoir is the comparative thinness of the spiral fibres anteriorly, and the 

 thickness of the longitudinal layer, which seems to afford compensation for the diminished strength 

 of the exterior coat. This deviation from the usual structure is doubtless in connection with the 

 enlarged posterior end of the ejaculatory duct, and the gradual blending of the cavity of the reser- 

 voir into it. The mass of the spiral fibres is grouped posteriorly, and in action would seem to com- 

 press the reservoir, so as to throw its contents forward to the gaping aperture of the duct. On 

 this account also (i. e., the grouping of the looped fibres posteriorly), the channel of communication 

 is long. The external layers, continued from the preceding division, pass about half-way back- 

 wards over the reservoir. Another peculiarity is the presence of numerous clear cells and 

 granules amongst the spiral fibres. Some of the cells contain nuclei; others do not. The 

 glandular papillae in the interior of the reservoir are large and prominent. The very great length 

 of the posterior chamber, as compared with the short anterior, is noteworthy. 



M. de Quatrefages seems to have devoted considerable attention to the anatomy of the fore- 

 going species (his Nemertes balmea). He represents the stylet-region as having the marginal sacs 

 rather behind the long central granular apparatus, each of the former possessing a carunculated 

 gland attached to its posterior end, while the latter has two longer structures of the same descrip- 

 tion. None of these carunculated appendages have been seen by me, since it can scarcely be 

 supposed he refers to the opaque granular condition of the space (at a, Plate XII, fig. 11) — 

 previously described. His account of the contents of the marginal stylet-sacs is erroneous ; for 

 though the position of the stylets is of no moment, the assertion (and corresponding figure) that 

 each has a developing basal apparatus attached to its extremity does not rest on facts. The 

 outline of the stylets given by this author is inaccurate, since no constriction is represented in 

 front of the head, and no mention made of their curvature. The other objections to his views are 

 noticed elsewhere. 



In Nemertes* Neesii the proboscis, while approaching that of N. gracilis in general size, and 

 the tenuity of the posterior region, is yet more closely allied to A. lactifloreus in the structure of 

 its comparatively short stylet-region proper (Plate XII, fig. 12). The floor of the anterior chamber 

 is furnished with very minute glands. The marginal stylet-sacs are small and somewhat 

 rounded, their ducts being occasionally spindle-shaped, from evident constrictions situated 

 respectively at the openings into the floor of the anterior chamber and the sac itself. The stylets 

 are at once distinguished by their short, stout form, and peculiar markings resembling the 

 longitudinal streaks in polished mahogany (Plate XI, fig. 12), which are due to irregularities 

 or furrows on the surface. The granular basal apparatus of the central stylet (X, Plate XI, 

 fig. 11) is short, and has only a slight constriction in the middle, so that the lateral line, from the 

 apex of the spike to the base of the former, is nearly straight. The opening of the ejaculatory duct 

 into the cavity (e) behind the floor of the anterior chamber is wide. The reservoir is much elongated, 

 and it may be observed that its soft fibres, as pressed between glasses, do not appear in a spiral 

 series down the sides of the cavity, but in the form of a dense felt-like arrangement ; yet, when 

 freed from pressure, their elaborate crossings are better shown than in most species (Plate XIV, 

 fig. 5). In the same region the longitudinal fibres are much developed anteriorly, though they are 

 only well seen on stretching the parts, otherwise the felt-like arrangement of the spiral fibres 

 obscures them. The glands of the reservoir are smaller and less distinct than in N. gracilis, espe- 

 cially anteriorly. The channel of communication with the posterior chamber is short and wide, and 

 in marked contrast with the same part in the latter species. The long posterior chamber has its 



