REPORT ON THE NEMERTEA. 35 



" 111 minute structure the anterior region quite corresponds with the tj^jical form, 

 presenting externally a layer of elastic fibrous tissue, which in transverse section presents 

 a series of circular fibres. The external longitudinal muscular coat is well developed. 

 The reticulated layer cuts the foregoing layer into sections, as usual in most other forms, 

 and the connecting bauds seem to be broad, the longitudinal belts rounded in transverse 

 section. The condition of the specimen, which is imperfectly preserved, however, 

 probably causes this layer to be more prominent, and the separation between the two 

 lonoitudinal coats wider. The inner loneritudinal muscular coat has the usual thickness 

 and appearance, and the same may be said of the inner circular muscular coat. The 

 basement layer is verj^ largely developed, and fills up a considerable part of the central 

 area. It is somewhat regularly streaked by a radiating series of granular channels. 

 Occasionally tortuous and numerous granular cells occur in it. The central granular 

 glandular tissue has mostly disappeared, but in minute structure it corresponds with that 

 in other forms. 



" The middle region of the organ presented no visible stylets, but otherwise it agrees 

 in general configuration with the typical form, though less definitely formed. The glands 

 of the posterior region are largely developed. 



" The posterior part of the proboscis sheath had a quantity of flocculent material 

 microscopically presenting numerous granular, and often nucleated cells, mixed with 

 granular material ; such might be connected with the proboscidian gland. 



" The mouth, as Professor Moseley observes, forms a well-marked aperture with a 

 frilled margin. It is proportionally the most distinct aperture yet observed. The 

 minute structure of the oesophageal region is similar to that of other forms, and it 

 terminates similarly. 



"The dendritic arrangement of the digestive system. Professor Moseley states, is the 

 most remarkable feature about Pelagonemertes, indeed it diff'ers from all other 

 Nemerteans. The condition of the organ in the other forms, however, renders the 

 arrangement less striking. In Nemertes gracilis, for instance, it is considerably divided. 

 Microscopically it agi'ees with other forms in cells, &c. Professor Moseley describes a 

 distinct anus in the young form, but the specimen may have been incomplete posteriorly. 

 It is certainly unusuallj^ distinct. The vascular system offers no particular feature of 

 interest so far as observed, and seems to follow the ordinary arrangement. The lateral 

 vessels appear to vary a little from the ordinary relation to the nerve-cords, being often 

 internal rather than inferior, but probably such is due to the yielding nature of the 

 tissues. The inner lining of the vessels is granular, and a few granular cells ajipear in 

 the centre, but the nature of such is problematical 



" The nerve-trunks are enveloped in a coating of nerve-cells. The branches from the 

 ganglia and nerve-cords are remarkably distinct, presenting a clear sheath and granular 

 axis cylinder. The gelatinous interstitial substance extends between the muscular 



