16 Records of the Indian Museum. [YoL. XIY, 



gills or tlie size of the animal ; in a posterior fragment with 118 pairs, 

 43 were mere tubercles, and indeed all but the last 20 were little more ; 

 in a specimen 100 mm. long, with 92 pairs, all but a few were well deve- 

 loped ; in the longest specimen, with 90 pairs, about half were tubercles 

 only. 



The length of the gills also varies. In an ordinary specimen they 

 are perhaps somewhat shorter than the diameter of the body ; but in 

 two examples of the present series they were very long, — about three 

 times as long as usual, — filamentous, tangled together and hence difficult 

 to count. In a third specimen of the same batch they were about twice 

 as long as usual ; but in the fourth and last in the tube they were not 

 noticeably longer than the ordinary. 



As can be seen, these variations seem to be independent of each 

 other ; nor can I connect them with the habitat except in a small degree. 

 The specimens just mentioned, with the very long gills, were all taken 

 from black mud at the edge of the lake, in about one foot of water, 

 where much decaying vegetation was present ; the length might be 

 correlated with deficiency of oxygen, — but one specimen had gills of 

 only normal length. The length of the animals may however have a 

 relation to the nature of the bottom in which they live ; thus those 

 living in soft mud at the edge of a stream were the shortest (the stream 

 was warm, and issued from a hot sulphur spring, — conditions which 

 might perhaps have checked growth) ; lengths of 45 — 70 mm. were 

 found in one foot of water in relatively stiff, peaty mud ; and specimens 

 90, 100, and 185 mm. were contained in the catches from the open lake, 

 in seven feet of water. These very long specimens were taken on a 

 bottom of extreme softness, indeed of semi-liquid consistency, in which 

 it would be necessary for cylindrical bodies to be of great length in 

 order to maintain a vertical position. 



Family MEGASCOLECIDAE. 

 Perionyx fulvus, Stephenson. 



Inle, Yawnghwe State, Southern Shan States ; soft mud in muddy stream in 

 \\ — 3 feet of water, fith March. 1917. N. Annandale. Four specimens. 

 (No. W. 108-1.) 



The species was hitherto only known from a single specimen taken in 

 Calcutta. I must here correct a mistake which has crept into my original 



account (10) ; the male pores are there said 

 to be " not very close together on segment 

 xviii." I do not know how the word " not " 

 crept in ; my original notes have " male 

 apertures very close together," and the 

 T, . o • r 7 • figure of the male area in my notes (which I 



Fin. 4. — rmonyx fnlvus ; regu)n P . •' • n 



of male apertures did not reproduce m the paper) is practically 

 a facsimile of the one I give here (fig. 4), 

 drawn from the present specimens, except that the apertures are there 

 even rather nearer together. 



As the type specimen is incomplete posteriorly, I may give the follow- 

 ing measurements ;■ — length 175 mm., thickness 4 mm. (max. 4-5) in 



