STKUCTUEE OF EARTHWORM ALLIED TO NEMERTODRILUS. 545 



are embedded in a gelatinous-looking matrix, which is more 

 abundant in proportion to the muscular tissue in the case of 

 the longitudinal coat. As to the fibres themselves, I find that, 

 as M. Cerfontaine has described in Lumbricus (8), both 

 those of the longitudinal and circular coat present a radiately 

 striate appearance, the striae converging towards a central 

 clear space. I have not taken any special means to investi- 

 gate thoroughly the histological structure of the muscles, I 

 only describe what I have seen in transverse and longitudinal 

 sections of the entire worm; but I have little doubt from what 

 I have been able to see that the results of M. Cerfontaine's 

 investigations into Lumbricus will hold for Libyodrilus 

 also. The matrix in which the fibres are embedded can hardly 

 be termed granular in Libyodrilus; it has a gelatinous 

 homogeneous appearance, and is but slightly affected by borax 

 carmine. It forms a specially thick layer (fig. 14) between 

 the end of the longitudinal muscular fibres and the perito- 

 neum. The fibres — both those of the circular and the longi- 

 tudinal coat — tend to be grouped into definite areas, which 

 are only separated from each other by the thickness of the 

 matrix lying between them. I quite agree [with M. Cerfon- 

 taine that there is nothing comparable to the septa described 

 by Claparede. No doubt such an appearance might be pro- 

 duced by great shrinking, caused by preservation in strong 

 alcohol without previously fixing the tissues. 



The arrangement of the fibres of both muscular coats is 

 regular, but the regularity is not so great as in certain species 

 of Lumbricus and AUolobophora ; each " compartment^' 

 is made up of fibres, which are three, four, or five deep — even 

 more sometimes. 



It is an interesting fact that in the young worm the fibres 

 are disposed much more nearly in the bipinnate fashion origi- 

 nally made known by the descriptions of Claparede. 



§ Ccelom and Intersegmental Septa. 

 The first septum separates Segments 4 — 5; in front of 

 this the pharynx is attached to the parietes by numerous muscu- 



VOL. XXXII, PART IV. NEW SER. 



