206 TRANSACTIONS, NATURAL HISTORY SOCIETY OF GLASGOW. 



.another specimen lately received from Prof. Bell the 

 right division is rather less than half the length of 

 the left. Prof. Bell has recently called attention to 

 two other specimens exhibiting a similar condition.* 

 In one of these the division took place about the 

 union of the middle with the posterior third, and 

 the left branch was slightly shorter than the right. 

 He tried to keep this specimen alive ; but after 

 some time the left branch became less active, and 

 ultimately both branches dropped off and the worm 

 died. The other specimen which came under his 

 notice was one of Lumbricus foetidus, but unfor- 

 tunately he was unable to describe it owing to its 

 imperfect preservation. The only other case of the 

 kind I have seen recorded is that of a worm 

 described by Mr. C. Robertson,t and now in the 

 University Museum, Oxford. In it the division takes 

 place at the 85th ring, and the two hinder parts are 

 equal and each is furnished with an anus. I think 

 it better not to say anything of the remarkable 

 little double worm recently found in New Zealand,}: 

 till a fuller description has been published. 



Although in some of the above cases the posterior 

 parts are unequal, it is probable that they were equal 

 at an early stage, but for some reason or other 

 developed unequally, as is known to be the case 

 frequently in double monsters of the higher animals. 



In conclusion, I may say that I consider that the 

 division which has taken place in these abnormal 

 -cases represents that which occurs normally in 

 Lumbriciis trapezoides, and is probably an attempted 

 reversion to an ancestral mode of development 

 which is handed down in L. trapezoides. It may be 

 that double monsters in the vertebrates are to be 

 accounted for in a somewhat similar manner. 



*•• Notice of two Lumbrici with bifid hinder eiuls." By Prof. Jeffrey Bell. Ann. Mag. 

 Nat. Hist. (5), vol. xvi. (1885), p. 475. 



t " Note on a Double Earthworm, Lumbrtcut terrestris." By C Robertson. Quart. Journ. 

 Micro. Sc, vol. vii. (18*57), p. 157. 



J ••Note on a curious Double Worm." By T. W. Kirk. Trans. Xew Zealand Inst., \o\. 

 six. (1886), p. 64. 



