BY J. J. FLETCHER. 
1555 
readily distinguishable from one another, and differ more in 
appearance than one can easily put into definable characters. Any- 
one having at his disposal only anterior fragments of a few speci- 
mens of the two new species, might easily be misled into thinking 
that he was dealing with species of Oryytodi'xlus. 
Perich,®ta enormis, n.sp. 
Nine complete (spirit) specimens, several of them young ones, 
from 50-87 mm. long, 3-4 mm. broad ; number of segments about 
200-220. (Four other incomplete but otherwise good specimens also 
examined). 
Agreeing with the foregoing species in most respects, but 
differing in regard to the number and arrangement both of the 
sette and of the genital papillse, and in the number of the cseca 
of the spermathec® ; the body is not so slender, and the dorsal 
pores seem to commence after segment x, the first two or three not 
always easy to see. 
Setae : the first dozen (occasionally one or two less, frequently 
a few more) setigerous segments with 8 set® per segment, in 
four couples as in P. attenuata ; then the number increases to 
1 2 — rarely 5 on one side of a segment and 4 on the other, or 
5 on each side — which number then continues fairly constant ; 
the additional set® making their appearance between the original 
second and third rows on each side, or one on either side of each 
original third row, or here and there one dorsad of the original 
outermost rows ; the two innermost (i.e. ventral) rows on each 
side straight throughout, a median ventral interval devoid of 
set® about twice that between the set® of the first and second 
rows on each side ; for some distance one or two of the other rows 
and the outermost one fairly straight also, leaving a broad 
median dorsal interval devoid of set® ; soon more and more of 
the set® become shifted dorsad, until in about the posterior half 
of the body all the rows but the two innermost on each side become 
more of less sinuously irregular, sometimes alternating irregularly 
