692 MR. F. E. BEDDARD ON NEW [DeC. 20, 



habit which might perhaps discount the value of the characters 

 aflForded by the clitellar epitlielium. Although the clitellar epithe- 

 lium is only one cell thick, it is made up of cells of two kinds : 

 there are large non- staining cells, imbedded among smaller cells loaded 

 with darkly staining granules. Plate XLV. fig. 5 illustrates the 

 structure of the clitellum, which, as will be seen, is not very much 

 thicker than the epidermic tissue of adjacent segments not nodified. 



The setse, as in other species, are strictly paired ; I could find no 

 setse upon the second segment of the body : I have already men- 

 tioned that in M. barwelli these setse are very small and easy to be 

 overlooked ; I could not find the least trace of them in the present 

 species. 



The muscular layers of the body-wall are remarkable in certain 

 points. The circular layer, as is shown in fig. 5, does not extend quite 

 up to the longitudinal layer : between the two is a space occupied by 

 a delicate connective tissue with interspersed nuclei ; in this layer 

 run the nerves, of which there are three main trunks in each seg- 

 ment. The muscle-fibres, when seen in transverse section, show the 

 characteristic appearance of the muscular fibres of the Leech in a 

 more distinct way than I have ever noticed in any Oligocheetous 

 worm : the layer of muscular substance in each fibre is very narrow 

 as compared to the central cavity, which is filled by a faintly granu- 

 lar matter ; this is not stained ; the fibres differ greatly in diameter, 

 the smaller ones being nearest to the epidermis. One might 

 perhaps speak of the layer which lies between the circular and 

 longitudinal muscles as a " nervous layer " ; it contains many small 

 nerve-twigs besides the main trunks already referred to. The 

 longitudinal muscular layer is, comparatively speaking, narrow ; its 

 fibres tend to be arranged in the bipinnate fashion which is so com- 

 mon, though not universal, among the higher Oligochseta. Here 

 also it was easy to see that each fibre has a central soft core. On 

 the whole the structure of the body-wall of the Annelid, with the 

 exception of course of the clitellum, is like that of Earthworms 

 rather than the aquatic genera ; but Phreoryctes, v/hich Claparede 

 ranged among his " Limicolse," has a body-wall which is also like 

 that of the higher Oligochseta ; so that this point of resemblance 

 is not conclusive as to the aflinities of Moniligaster. 



Internal Anatomy. 



The internal structure of this new species of Moniligaster is not 

 widely different from that of Moniligaster barwelli ; there are four 

 thickened septa which divide segments v./ix. Probably the exis- 

 tence of this number of septa is a character of generic importance, 

 as they seem to occur in M. beddardi as well as in the two species 

 referred to. The alimentary canal, again, presents no differences 

 from that of other species ; there are no calciferous glands, and there 

 appears to be no vascular tract of the oesophagus which in so many 

 Oligochseta replaces functionally these glands; the usual three 

 gizzards are present, commencing in the xiiith segment. The 

 nephridia have a large csecum as in other species ; I observed the 



