196 PAUL S. WELCH. 



The length of the duplicated parts is a matter of considerable 

 variation and the only general relation discovered is that the 

 longer ones occur on the posterior end. Up to date, the writer 

 has not found an anterior bifurcation to exceed six somites, 

 while posterior ones may include seventeen somites. Instances 

 were observed in which the posterior branches constituted more 

 than one half the total length of the body. Many anterior 

 bifurcations are only one somite in extent, two and three being 

 also common. Posterior bifurcations may be short, however, 

 comprising but one somite. A trunk portion of several somites 

 extent is always present, no instances having been seen of such 

 narrow connection of duplicated parts as described by Weber 

 (1917) for Helodrilus caliginosus trapezoides. 



EMERGENCE OF BIFURCATE INDIVIDUALS. 



Among approximately four thousand young worms just 

 emerged from cocoons the writer found only ten which exhibited 

 bifurcations. These were all alive and active. Three were 

 slightly bifid both anteriorly and posteriorly; six had slight 

 anterior bifurcations and normal posterior extremities; and one 

 had a very slight anterior bifurcation and a very deep bifurcation 

 of the posterior end. 



The discovery of these ten free individuals indicates clearly 

 that while emergence is possible it is really a rarity. Since nine 

 had completely emerged before they were detected, their method 

 of escape is unknown. The remaining one, caught in the act, 

 was emerging backward, the normal posterior end going in 

 advance. This form of escape appeared to be effective, although 

 the bifurcated anterior end gave some trouble in traversing the 

 cocoon neck. This observation suggests the possibility that the 

 above-mentioned individuals with normal posterior ends emerged 

 backwards. Added weight is given to this suggestion by the 

 repeated observation that in the escape efforts of normal indi- 

 viduals the posterior ends were often projected through the 

 cocoon neck. It seems that the escape of the specimen with 

 shallow anterior bifurcation and very deep posterior one of 

 necessity must have been with the anterior end in advance 



