18fl2.] OF THE GENUS PERICHiETA. 165" 



of a part of the atrium ; the setse are interrupted for a short space 

 on either side of each pore, which, however, he directly in the line 

 of the setse. I counted seventeen setse hetween the male pores. 



I could find no genital or copulatory papillce of any kind. 



The spermathecal pores were very evident in all the specimens ; 

 they lie between segments vii./viii. 



The dorsal pores commence between segments xii./xiii. 



The anterior segments of the body are bi- or tri-annulate. 



With regard to the internal anatomy of the species, I only 

 direct attention to those points which are known to be of importance 

 in the discrimination of species. The position of the gizzard is 

 perfectly normal ; it lies in segments viii.-x., and the septa between 

 these segments have nearly entirely disappeared, being represented 

 only by a few ligaments binding the gizzard to the parietes. The 

 intestine is very remarkable on account of the fact that there are no 

 ccEca. I looked for these structures very carefully, and entirely 

 failed to discover them ; they are always (according to my ex- 

 perience) quite easy to find when present. I must therefore 

 conclude that the present species is unique in the absence of cseca. 

 Although there appears to be no Earthworm known on other grounds 

 referable to the genus Terichceta is. *.) which possesses no intestinal 

 cseca, Mr. Fletcher ^ has described a Megascolex in which cseca are 

 present. In Perichtsta queens! an dica, a worm with " interrupted 

 circles of setse," there are a pair of lateral cseca arising from the 

 intestine in segment xxv. and directed anteriorly, as in all true 

 PericlicetcB with the exception of PericJiaeta taprohanae ^ ; these two 

 species evidently render it impossible to define strictly the genera 

 Perichtsta and Megascolex, though as a matter of convenience those 

 names maybe, for the present at least, retained until more exceptions 

 are made known. In other particulars the alimentary tract of this 

 Earthworm does not diverge from the normal. 



The intersegmental septa commence to be distinct after the fourth 

 segment ; the first four septa, viz. those bounding segments v.-vii., are 

 rather thickened ; as are also the first two septa which lie behind the 

 gizzard, that is to say those which separate segments x./xi. and xi./xii. 

 The thick septa in front of the gizzard are covered with very con- 

 spicuous nephridial tufts. 



The sperm-sacs lie in segments x., xi., and xii. 



The atria consist as usual of a thick muscular duct bent upon 

 itself and of a glandular portion consisting of ramifying cseca ; the 

 latter is fairly compact except where it is cleft at its junction with 

 the non-glandular part. The glandular part is much smaller than 

 is usual in this genus, and is entirely limited to the xviiith segment. 

 The muscular duct is unprovided with a dilated sac at its extremity. 



There is only a single pair of spermathecce, which lie in segment viii. 

 They also are small ; and, as the facts contained in this account are 

 based upon the dissection of several examples, I may emphasize the 



^ " Notes on Australian Earthworms, Part II.," P. Linn. Soc. N. S, W. ser. 2, 

 vol. i. p. 964. 



'^ I am not certain as to PericJusta ceylotma. 



