PACIFIC COAST OLIGOCH ETA. 137 
INTERIOR CHARACTERS. 
Gizzards, two in vii and yiil. 
Calciferous diverticula. Three pairs in xy, xvi and xvii. 
Sacculated intestine commences in xviii. 
Typhlosole present. 
Prostates slender, confined each to one somite. 
Spermathece. The apical part a trifle smaller than the basal. Both parts 
much flattened. A very small diverticulum pointing forwards. 
Nephridia in four rows on either side of the median line. The posterior ne- 
phridia with celomic glandular mantle. Nephridia in each somite of about equal 
size. Nephridia d and d about equidistant as a and a. The most ventral part of 
nephridium @ not covered by the mantle. The clitellar nephridia larger than those 
anterior to clitellum. 
DETAILED DESCRIPTION. 
Size. The specimens had been slowly killed and extended before hardening. 
All the specimens were curved backwards, thus with the dorsal line on the inner 
margin of the crescent, causing the male pores to be situated at the greatest bend on 
the outer margin of the crescent. Most terricole curve the opposite way. 
Shape of segments. The first ten somites are very nearly of the same diameter 
in the direction from head to tail. Somites xi and xii are slightly narrower. The 
clitellum which comprises somites xiii to xx shows plainly the intersegmental grooves. 
The posterior somites are of a somewhat shorter diameter than xi and xii. All the 
anterior somites including the most posterior ones of the clitellum are sculptured by 
longitudinal furrows running in the diameter from head to tail. This corrugation is 
seen all around the body, and gives the anterior part of the worm a very marked 
appearance. The posterior somites show a fainter corrugation. All somites are 
3-ringed, except those of the clitellum. 
Prostomium is long and pointed and slightly curved upwards (figs. 57 and 58) 
and is a trifle longer than somite ii. Inall the specimens but one, somite i, was nearly 
entirely retracted in the buccal cavity, and when viewed from the exterior only a 
short portion of its dorsal part could be seen (fig. 58) and the prostomium appeared 
as if projecting from somite ii. One specimen had somite i extended as figured 
in fig. 59. Dr. Michaelsen has remarked a somewhat similar retraction of somite i in 
B. kafuruensis. Spermathecal pores as usual, vii—vili and viii-—ix. 
Clitellum is narrower than the surrounding somites. It is strongly corrugated, 
especially at the anterior and posterior margins. The prostate pores are, as usual, in 
xvii and xix. The exterior part of the genital region is very characteristic. In 
young specimens the two prostate pores are connected by a deep furrow in the 
center of which is seen the slight depression for the male pore. In the two fully 
adult specimens, however, the two anterior prostate pores were each situated on a 
very large globular papilla, surrounded by a deep fossa; while no such papilla and 
fossa characterized the posterior pair of prostate pores. In fact, these posterior pores 
