BIFURCATION IN EMBRYOS OF TUBIFEX. 



cation as an embryonic phenomenon in any of the lower famiies 

 of the Oligochseta. 



4. Diverse forms of bifurcation involving both extremities of 

 the body occur in either simple or compound form. 



5. Of more than four thousand recently emerged worms exam- 

 ined only ten bifid individuals were found. Any departure from 

 normal body form involving increase in diameter constitutes an 

 extremely effective barrier to escape from the cocoon and prac- 

 tically all of the numerous abnormalities are automatically 

 eliminated. 



6. While bifid worms may live for long periods of time im- 

 prisoned within the cocoons, emergence is a rarity. 



7. Attempts to rear bifid individuals have thus far been 

 unsuccessful. 



8. An examination of more than one thousand worms from 

 natural habitats and representing various stages of maturity 

 yielded no bifid forms. 



9. A preliminary morphological study, based principally on 

 the setae, the nervous system, the nephridia, and the circulatory 

 system, shows the body region of these monsters to be double in 

 composition while the bifurcate portions simulate the normal 

 tubificid structure. 



LITERATURE CITED. 



Abel, M. 



'02 Beitrage zur Kenntnis der Regenerationsvorgange bei den limicolen Oligo- 



chaten. Zeit. f. wiss. Zool., 73: 1-74. 3 pi. 

 Dixon, G. C. 



'15 Tubifex. Liverpool Marine Biology Committee Memoirs, XXIII. , 100 



pp., 7 pi., 2 text fig. 

 Duges, A. 



'28 Recherches sur la circulation, la respiration et la reproduction des Annelides 



abranches. Ann. Sci. Nat., 15: 284-337. 3 pi- (Original not seen.) 

 Kleinenberg, N. 



'78 Sullo sviluppo del Lumbricus trapezoides. Naples, 56 pp. 3 pi. (Original 



not seen.) 

 '79 The Development of the Earth-worm Lumbricus trapezoides Duges. Quart. 



Journ. Micr. Sci. (N.S.), 19: 206-244, 3 pi. 

 Korschelt, E. 



'04 Ueber Doppelbindungen bei Lumbriciden. Zool. Jahrb., Suppl. Bd., 7: 

 257-300. 2 pi. 



