MELANENCHYTRAEUS SOLlFUGUS 



examined anatomically. Their external opening lies near the anterior limit 

 of the 5th segment. A cylindrical duct made of cylindrical cells leads 

 from the external opening to a wide cavity, which extends at its base into 

 closed appendages or diverticula. These are only two larger on the right 

 side, three smaller on the left. The two spermathecae communicate with 

 one another, or, more exactly, they form a continuous whole, which traverses 

 the dorsal portion of the intestine, without opening into the latter. 



This anatomical description and the accompanying plate show so many 

 singular facts in the structure of the worm examined, that I feel justified 

 in forming for it a new genus, of which it is the only known species. From 

 its obscure colour and light-shunning habits, I have called it Melanenchytraeus 

 solifugus. 



I translate here the diagnosis which I have already published in the 

 Rendiconti della R. Accademia dei Lincei} 



Melanenchytraeus, Emery. 



Hypoderm pigmented. All the segments with dorsal and ventral 

 bundles of 4 chaetae each. The latter are slightly sigmoid, longer in the 

 foremost segments. No ventral bundle in the 12th segment, which bears the 

 opening of the sperm-duct. The latter is very long, and forms a coiled loop, 

 extending back to the 15th segment. Above the spherical bulb, which 

 forms its distal end, it presents a fusiform swelling ; spermiducal glands are 

 present. The sperm-sacs are ample, extending through several segments. 

 The spermothecae do not open into the intestine ; they are continuous with 

 one another, and bear at the base of their ampullae two or three diverticles 

 each. The nephridia are very much convoluted, with few nuclei. The dorsal 

 vessel begins in the 12th segment, and includes a cardiac gland. A cephalic 

 pore is present, but no dorsal pores. The epithelium of the pharynx contains 

 branched pigmented cells. There are no salivary glands, and no distinct limit 

 separates the oesophagus from the intestine. In segments 4-8 the body 

 cavity is largely taken up by unicellular glands, which, by means of long and 

 very thin prolongations, reach the surface of the skin near the ventral bundles 

 of chaetae. 



M. solifugus, Emery. 



The largest specimens are a little over one centimetre in length ; the 

 diameter of specimens preserved in spirits and moistened in water is about 

 one-third of a millimetre. The body is cylindrical, tapering imperceptibly 

 towards the hindmost extremity. The cephalic lobe is rounded. I counted 

 53 segments in one specimen. Colour dark brown, nearly black. 



The sigmoid chaetae, the cardiac body, and the much convoluted nephridia 

 assign to Melanenchytraeus a position near Mesenchytraeus. It differs from 

 the latter chiefly by the long and complicated sperm-duct. The dark 

 colouring of the hypoderm and other organs has not been observed in any 

 other member of the Enchytraeidse. 



^ Vol. VII., 1° sem., ser. 5. Seduta del 6 marso, 1898, p. no. 



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