30 MR. F. E. BEDDARD ON EARTHWORMS [Jail. 5, 



The prosfomium is large, being larger than the diameter of the 

 first segment. 



The sette are disposed precisely as in Microscoleoc modestus : that 

 is to say, the setae are not in closely approximated pairs, and the 

 distance between seta 1 and seta 2 is less than that between setae 3 

 and 4. The diagram given by Rosa of the setae of M. modestus 

 would express, so far as I can make out, the relations of the setae in 

 M. algeriensis exactly. There is nothing noteworthy in the form of 

 the setje. As in other Earthworms, the four setae of each side of the 

 body in each segment are connected by muscular strands which 

 favours, it may be supposed, their simultaneous movement. This 

 muscle in Microscolex is easily overlooked, owing to its great thin- 

 ness ; it is not more than two fibres thick. 



The clitellum is complete (forming, that is, a ring) and occupies 

 segments xiv.-xvii. with a part of xiii. Its structure is like that of 

 other Earthworms. 



I could find no dorsal pores. 



The cdimentary tract is peculiar frpm the absence of a gizzard, of 

 which traces appear to exist in other species of Microscolex ; for in 

 M. dubius Rosa speaks of " un ventriglio rudimentale, piatto, in 

 forma di coppa ; " as to the only other known form, Microscolex 

 modestus, Rosa found that " il ventriglio esiste, ma cosi rudimentale 

 da non potersene veder le traccie che nelle sezioni." It is not always 

 possible to detect the presence or absence of a gizzard without 

 having recourse to section cutting. Pontodrilus, for example, is 

 stated by Perrier to be without this special region of the oeso- 

 phagus ; but it is obviously present, though certainly much reduced, 

 when the anterior region of the worm's body is examined by means 

 of sections. 



The pharynx ends in the third or fourth segment, and, as in other 

 Earthworms, there are masses of glands upon the dorsal surface. 

 These glands, which seem to represent a part of the system of septal 

 glands in the lower Oligochaeta, are not confined, in Microscolex 

 algeriensis, to the pharyngeal region of the alimentary tract ; they 

 extend back as far as the ninth segment, and therefore suggest 

 more clearly the septal glands, with which they must surely be 

 homologous. It is interesting to recall the fact that these glands 

 occur also in Ocnerodrilus, which is another form near to the border 

 line between the terricolous and limicolous Oligochaeta, though 

 nearer to the latter than is Microscolex. 



The oesophagus of Microscolex algeriensis is divided into two 

 regions ; up to the end of segment vii. it is not markedly vascular, 

 and the hving epithelium is composed of more densely packed cells, 

 which gives it a more deeply stained appearance under the micro- 

 scope. The rest of the oesophagus has a richly-developed vascular 

 network, and the epithelium appears to have a looser texture, the 

 cells being less tightly packed; from this circumstance the posterior 

 region of the oesophagus looks paler in sections. In tlie xvth 

 segment the oesophagus becomes much narrower and then suddenly 

 widens into the intestine which commences in the xvith segment. 



