440 E. A. ANDREWS. 
The abnormality of this specimen, A, thus expresses itself 
not only in the duplication of the posterior somites but in an 
elongation of the trunk upon one side with partial formation of 
somites there. 
The second specimen, B, is much less conspicuously bifid, 
having only a small bud-like outgrowth upon its left side near 
the posterior end, as shown in fig. 6. There is here no doubt 
that the right terminal is the normal continuation of the body 
while the left terminal is of much subordinate importance. 
This individual was sexually mature like the other; dis- 
section of the anterior region showed that the reproductive 
organs were perfect and mature and that the dorsal receptacle 
contained sperm; there were also two “ spermatophores ”’ at- 
tached to the exterior upon the ventral side.! 
A very important peculiarity of this specimen is seen in fig. 
6, that is that all the somites posterior to the 59th are short 
and crowded with numerous double or abnormal rings, and that 
all this posterior region is noticeably narrower than the anterior, 
so that we at once infer, from the specimen, that all the region 
posterior to the 59th somite is a new formation due to re- 
generation of the original terminal. This seems to be a pretty 
safe conclusion, though there is still the chance that the nar- 
rowness of this region may have been due to incomplete de- 
velopment, to some deficiency in the early embryo or larva. 
The entire number of somites as counted on the right side, 
where several split or double rings increase the number, is 
103, and an anal piece so bent ventrally as to be invisible in the 
dorsal view, fig. 6. Of these about nine are posterior to the 
bifurcation, counting the anal piece as one; in the left lateral 
process there are also nine divisions, including the final or anal 
piece, which, however, shows no sign of an anal opening. 
The dorsal and ventral views, figs. 7 and 8, show that there 
are considerable irregularities in the somites anterior to as 
1 T hope to show elsewhere that in A. foetida the dorsally placed sperm- 
receptacles are filled during conjugation, and that the so-called ‘ spermato- 
phores” are almost accidental structures, which fall off soon after the act of 
conjugation. 
