DESCRIPTIONS OF GENERA AND SPECIES 591 



Definition. Length, 45 mm. ; breadth, I mm.; segments, 96. Penial sefae with transverse 

 rows of denticles at extremity. Hob. Malakalla, E. Africa. 



This species is the smallest known Eudrilid. The setae are very delicate, and 

 the distance between the four pairs is equal. There appears to be but little pigment 

 in the skin since the colour is described as being yellowish in front and grey behind. 



Genus MEGACHAETA, MICHAELSEN. 



DEFINITION. Setae gradually diminishing in size dorsally, those nearest ventral 

 median line being largest. Male genital pore upon XVII. A single median 

 spermathocal sac opens on to segment XIII. Penial setae present. 



This genus is at present only imperfectly known, none of the examples of either 

 of the two species having been fully mature. These two species Megachaeta tennis 

 and M. alba are both East African. 



The most marked external peculiarity concerns the setae. The ventral setae are 

 much stouter than the dorsal, and there is a regular diminution in size in passing 

 from the ventralmost seta to the dorsalinost. Moreover in the anterior segments 

 the setae are not so large as in the following segments. The characters of the setae 

 are curiously paralleled in the genus Gordiodrilus (which see), which is not in other 

 respects a near ally of the present worm. MICHAELSEN remarks that the nephridio- 

 pores are not visible. It may be that this genus, like Libyodrilus, has an integumental 

 plexus ; but we have no knowledge upon the point. The alimentary canal has 

 a gizzard in segment v or vi; it appears to have neither calciferous glands nor 

 ventral diverticula ; the genital organs are also imperfectly known. In Megachaeta 

 alba only a single pair of sperm-duct funnels were found lying in segment xi. The 

 spermiducal glands are tubular and each has a sac of penial setae ; or rather a single 

 seta belongs to each. The aperture upon the thirteenth segment leads into a sac, 

 which extends back as far as the seventeenth segment. This sac gives off lateral 

 outgrowths which communicate with compact glands attached to the septa. The 

 nature of these is at present very doubtful, and they are not very fully described 

 by MICHAELSEN. The following is his description : 



'Durch die Oeffnung im 13. Segment gelangt man in ein grosses muskuloses, sich auch etwas 

 nach vorne ausdehnendes Atrium. Nach hinten setzt sich dieses Atrium in eine lange unregelmassig 

 angeschwollene und gekriimmte Samentasche fort, die sich bis in das 17. Segment erstreckt. Auch 

 die Samentasche ist muskulos, besonders ihr distaler Teil. Seitlich und unterhalb des Atriums und des 

 distalen Samentaschenendes haben sich starke Wucherungen gebildet, die bei einem ziemlich unreifen 

 Exemplar fliigelformig in die Leibeshohle hineinragten. Bei einem weiter ausgebildeten Exemplar zogen 



