78 ]\rr. F. E. Beddard on a 



P. Smithii the dorsal are tlie larger, but in P. Ileydeai 

 Noll* figures the ventral setgef as being slightly the larger, 

 and in P. emissarius \ the dorsal seta3 diminish in size pos- 

 teriorly and finally disappear. In Megachceta there is a still 

 closer resemblance to Gordiodrilus tenuis, for the two ventral 

 seta3 are not only larger than the dorsal, but the individual 

 setai of each ventral pair are unequal in size, the innermost 

 of the two being distinctly the larger. But there is also a 

 regular and progressive increase in size, affecting not only the 

 ventral, but also the lateral seta3. Even in Perichceta, with 

 the circle of numerous setffi in each segment, the ventralmost 

 ones are in a few cases (e. g. in P. Houlhti) decidedly larger 

 than the rest. These cases are interesting as showing the 

 differentiation of a dorsal and ventral surface, which, so far 

 as the seta3 are concerned, is not always apparent in the 

 Oligochjeta. It would add to the interest if it could be 

 ascertained whether there is any corresponding moditication 

 of habit ; whether, for example, Megachceta and Gordiodrilus 

 frequent the surface of the soil rather than its depths. 



The clitellum was not apparent until the worm was 

 examined by means of sections. It is very extensive, reach- 

 ing from the xivtli to about the xxviith segment, and is only 

 developed dorsally. 



I could not find any dorsal pores. 



The 7ie]jhridiopores open in front of the lateral sette. 



Internal Structure. 



Having only one specimen of this Oligochgete for examina- 

 tion, I am not able to give so complete an account of 

 Gordiodrilus tenuis as I could wish, and as I have been 

 able to give concerning the other species of the genus. My 

 account is, moreover, rendered less complete than it would 

 otherwise have been by the fact that the sections were in 

 many places insufficiently stained. Nevertheless I have been 

 able to make out the principal facts which bear upon the 

 systematic position of the Annelid. The thickness of the 

 cuticle was very remarkable; it appeared to me to be propor- 

 tionately thicker than in any earthworm which I have 



* " Ueber einen iieuen Eiugelwurm des Ilheiiis," Arch. f. Naturg. 

 Jahrg. 40, p. 260. 



t There is a little confusion about this matter. Claparede's Nemo- 

 (IrilusJiliformiK, which Vejdovsky believes to be identical with Noll's 

 P. Heijdeni, is stated to have longer dorsal seta3 by both Claparede and 

 Vejdovskj', though Claparede's figures show the reverse. 



X Forbes, " On an American Earthworm of the Family Phreoryctidae," 

 Bull. Illiu. Lab. vol. iii. p. 107. 



