1892.] Bifurcated Annelids. 729 
authenticated case of double-headedness amongst annelids, 
was seen in a specimen of Typhlosyllis variegatus Gr. from 
Madeira. As shown in fig. 6, the left head has two somites 
more than the right. As the author notes, and as the figure 
indicates, the specimen appears to have lost its original head 
and to have grown there two new ones, having been broken off 
just anterior to the pharyngeal tube. This, with its dentition, 
is of the normal size and could not be used in connection with 
either of the two small heads. 
In the same family a case of bifurcation of the posterior 
end in Procærea tardigrada Wb. was observed in North Carolina 
by E. A. Andrews (13). Among several hundred specimens 
seen during two successive seasons two cases of such bifurca- 
tions seem to have occurred, one being found by Prof. 
Nachtreib. In the one represented in fig. 9 the animal moved 
actively, each long tail crawling like the normal termination 
of the body. Each has also the peculiar red transverse bands 
of this species. Though nearly equal in length and diameter 
the two tails have unequally perfected posterior tips, as seen 
in figs. 11 and 12, the right lacking the normal anal cirri. In 
fact this right tail was interpreted as a sort of lateral out- 
growth from the more perfect left tail. This was one of the 
common non-sexual individuals in which the sexual head was 
forming upon the fourteenth somite as usual, preparatory to a 
separation of all the following region as a sexual individual, 
in this case, a female, which would then have two tails to bur- 
den it in its more active mature life. 
The only other case that I find record of is that of a Nereis 
pelagica, observed by F. J. Bell (14), a specimen sent from 
Guernsey and exhibited at a meeting of the Zoological Society 
of London. Beyond the fact that the specimen was bifid at 
_ the posterior end no information is given concerning it. 
Thus among the many hundred annelids carefully studied 
and among the thousands more or less casually observed there 
were found, as far as this imperfect record extends, only about 
twenty cases of bifid ends. Of these only two were cases of 
duplication of the head end. Only eight cases have been fig- 
