REPORT ON THE NEMERTEA. " 21 



with similar eyes. The posterior boundary especially being so distinct as almost to 

 make a special row. 



" Behind these a band of similar eyes runs upwards and slightly forwards, a consider- 

 able interval on the summit of the dorsum separating those of each side. 



" The cephalic furrows slope outwards and backwards on each side to the margins 

 dorsally, and from the latter point are continued ventraUy outwards and forwards. 



" So far as can be observed in this form only a single aperture exists for the proboscis 

 and mouth. This forms a well-marlced slit in the ventral surface, a little behind the 

 tip of the snout 



" lii minute structure the proboscis corresponds to that of the typical form .... 

 the stj/let is simple and normal." 



To this description of the external characters I have nothing to add, but may proceed 

 to remark that the examination of the internal structure by means of sections has 

 revealed the significance of the white lateral stripe, noticed by Professor M'Intosh as not 

 being ', due to pigment. It is, indeed, a peculiar feature by which this species is 

 characterised, and which I have hitherto not observed in other Nemertea. All along the 

 extent of this lateral and longitudinal whitish line (PI. IX. fig. 8) the sections show 

 the presence of numerous glandular (or sensory ?) cavities, opening to the exterior by very 

 numerous pores piercing the integument, and both accumulated at, and limited to, the 

 region where the dorsal musculature merges into the ventral (PL XV. fig. 11), and where, 

 as in so many Hoplonemertea, the muscularity of the body-wall is reduced to a minimum, 

 i.e., in the right and left lateral line. In the posterior portion of the body these organs 

 were no longer present ; anteriorly, however, they could be traced even in the head (PI. X. 

 fig. 3, gls.). Further details about their structure will be given in the anatomical part of 

 this Keport. 



The other chief peculiarities of the species which are revealed by a study of the 

 sections, and which must be briefly enumerated in this summarising description, are : — 

 the situation of the longitudinal nerve-stems, in the portion of the body where the 

 intestinal caeca are clearly developed, above these c^ca about one-third or halfway 

 between the lateral margin and the proboscidian sheath. It should be remarked that 

 this arrangement is the opposite of what is observed in Drepanophorus, where the 

 longitudinal nerve-stems, as elsewhere described, have their course beloiv the intestine, or 

 below the lateral cseca. The significance of this difierent arrangement wiU be elsewhere 

 discussed ; in itself it is a feature very much facilitating the discrimination of Amphi- 

 porus moseleyi from other Amphipori, where the nerve-stems are found much more 

 strictly laterally, at least in those hitherto known. There is a very distinct commissure 

 between the lonmtudinal stems above the anus. 



Another most characteristic feature which may generally be distinguished in every 

 transverse section of the animal, especially when it is ripe for reproduction, is the situation 



\ 



