136 Transactions. — Zoology. 



Beddard, in his " Monograph," does not say that there is a 

 single pair of testes, and I have not Spencer's paper at hand 

 to refer to ; anyhow, D. walhalla differs in having five pairs 

 of spermathecae and 20-24 chaetae per segment. D. maples- 

 toni has, moreover, spermiducal glands and spermathecse of 

 quite a different form (though there is no diverticulum) ; it 

 differs also in the arrangement of the genital papillae. In 

 the latter matter D. lindti, Spencer,* and D. dicksonia, 

 Spencer,! bear a closer resemblance to our own species 

 than do any of the others, but in all other features are 

 very different. It is possible, of course, that D. chathamensis 

 has been introduced into the Chathams from Australia by 

 man, though it is noteworthy that it differs from all those 

 twenty-six other species carefully examined by Spencer and 

 by Fletcher. 



4. Pontodrilus chathamensis, Michaelsen = P. matsushi- 

 mensis, var. chathamensis, Mich. 



Of this worm I have a good supply of material, partly 

 collected, as I have said, by Mr. J. J. Fougere, to whom I am 

 indebted for fourteen individuals preserved in formol, and 

 partly by Mr. H. B. Kirk, who handed me ten individuals 

 preserved in alcohol. 



The genus Pontodrilus is the only earthworm that lives 

 actually within reach of the sea — in fact, between tide-marks. 

 For reasons discussed below I believe this Chatham Islands 

 form is worthy of being considered a distinct species, while 

 Michaelsen, who, it is true, had very poor material, regards 

 it as a local variety of a Japanese species. 



Colour. — The formol specimens are pale-buff, distinctly 

 pink anteriorly, with a brown clitellum. 



Dimensions. — The length of the formol specimens is about 

 4-J- in. ; some attain a length of 5 in. The alcoholic individuals, 

 however, average only 3 in., though both sets are mature. The 

 postclitellian diameter is xe m - m DOt, b lots. The worm con- 

 tains about 80 to 130 segments, long and triannulate in 

 posterior region, while the anterior segments are even quin- 

 quiannulate. The animal is cylindrical. 



The prostommm is prolonged into the dorsum of the buccal 

 segment for fully a quarter the length of the latter. All my 

 specimens show the prolongation quite distinctly, but the 

 lateral furrows do not reach the posterior groove of the buccal 

 segment, as in the figure given by Jizuka. 



The chcetce have the usual arrangement in four couples, 

 the individuals of which are rather far apart : ab = cd = 3, 

 L = 5, V = 6, D = 8. 



* (2), p. 54. 

 t (1), p. 16. 



