i9o8.] 



W. M1CHAE1.SEN : Oligochœta of the Indian Empire and Ceylon. 



185 



Fig. 16. 

 Megascolex 

 hendersoni. 



ments ij , 18 and 19, that is to say, at the intersegmental furrows 17-18, 18-19 ^^^ 

 19-20, about opposite the interspace between the setae h and c. The papillae of the first 

 pair at the intersegmental furrow 17-18, in each of the four present specimens, are 

 longitudinally, but not laterally, narrower than the others. The papillae of the second 

 pair in the intersegmental furrow 18-19 ^^^ united at their medial- 

 anterior border to the papillae of the male pores. The ventral part 

 of segments 17 and 20 is swollen, glandular, and somewhat over- 

 hanging the space between them, i.e., the anterior part of segment 

 18 and the posterior part of segment 19. The lateral ends of 

 these thickenings lean against the copulatory papillae of the first 

 and third pair, and are connected by a pair of more or less dis- 

 tinct longitudinal walls, which run outside the copulatory papillae, 

 crossing the i8th segment. The ridges of these lateral thicken- 

 ings together with the longitudinal walls, marked by the copulatory 

 papillae, define a male area, which is mostly somewhat but not 

 much depressed. 



Internal Anatomy. — S e p t u m 6-7 is very tender, septa 

 7-8— 13-14 (or 14-15 ?) are thickened, especially septa lo-ii and 

 11-12, which are very strong, the others gradually less so. 



Alimentary tract: A very large gizzard, in one of the larger specimens 

 measuring 8 mm. in length and 5 mm. in thickness, lies before the tender septum 6-7. 

 The œsophagus is plain in segments 7 — 11 and segmentally swollen, nearly globular 

 in segments 12 and 13. In the 14th segment there are rather thicker swellings, which 

 are, however, confined to the lateral parts of the œsophagus ; these appear almost like 

 a pair of thick, bean-shaped calciferous glands, but they are not strictly set off from 

 the œsophagus, being merely lateral sacculations of the latter, their lumina not being 

 separated from the general lumen of the œsophagus. The walls of these lateral diver- 

 ticulum-like organs of the 14th segment as well as those of the swellings in the 12th and 

 13th segments have the lamellated structure of real calciferous glands. In the 15th 

 segment the œsophagus is narrow. The wide (in the anterior part laterally sacculated) 

 intestine suddenly begins in the i6th segment. There is no distinct typhlosole. 



Circulatory system: Dorsal vessel simple. I^ast hearts in the 13th segment. 



Nephridial system micronephric, consisting of very small scattered ne- 

 phridial villi. 



Anterior male organs: Two pairs of moderately large (apparently free?) 

 sperm-duct-funnels in the I oth and nth segments attached to septa lo-ii and 11-12. 

 Two pairs of loose racemose sperm-sacs depending from septa 9-10 and 11-12 into the 

 9th and I2th segments. The sperm-sacs of the 12th segment are distinctly larger than 

 those of the anterior pair in the 9th segment. There seem tobe no testicular vesicles, 

 but I saw what seemed to be special strings and cœlomic membranes expanding 

 between septa 9-10 — lo-ii and lo-ii — 11-12. I did not see the testes. 



The prostates are confined to the i8th segment, the septa of which seem to be 

 somewhat widened out by them. The glandular part is irregularly disc-shaped or 



