PACIFIC COAST OLIGOCH TA. 131 
diverticula is distinct. The nuclei of the anterior pair are round while those of the 
posterior pair are more oval, and the cells of the latter pair are not separated by dis- 
tinct walls. They contain also numerous vacuoles or bladder-like bodies, some of 
which deatch themselves from the main body of the organ. 
Figures 27 and 28 represent the anterior pair, 29 and 30 the posterior pair of 
calciferous diverticula seen respectively under high and low power. The posterior 
pairs only were found covered by chloragogen cells. These differences in structure I 
also found in the ealciferous diverticula of the following species: Benhamia palmi- 
cola and rugosa, and they probably hold good with all the species of Benhamia. 
Typhlosole exists in somites xvil or xviii to xxii, and is greatly developed as 
regards length, width and depth (figs. 7 and 14). It is widest and deepest in somite 
xix, tapering or diminishing both anteriorly and posteriorly. In the following species 
the typhlosole is much smaller. 
Spermathece. The two pairs as usual in vii—vili and yiii-ix. The form of the 
spermatheca and its diverticula may be best understood from the flgures 54 and 39, 
The pores come rather close together in a general groove below the ventral ganglion. 
There is a muscular and a glandular part, and the spermatozoa were fonnd as usual 
principally in the diverticula. 
Spermducts and rosettes. The only peculiarity of the spermducts is that they 
are thickened in somites xviii, xvii and xvi. In xy the duct narrows, and continues 
forward, with about half the thickness it possesses in the above posterior somites. The 
thickening is due to an increase of a circular muscular layer (figs. 7, 11, 12, 15, 56, 
307). The rosettes are in x, xi, as usual. 
Prostates. The usual two pairs are in xvii and xix. The lower part is long, 
slender and muscular, while the upper thicker part is glandular. This glandular part 
consists of only one layer of cells, covered by a thin epithelium. The glandular cells 
are of different length, as shown in fig. 32. The muscular part consists mainly of a 
thick layer of circular muscles (fig. 386), lined by a very thin layer of interior epi- 
thelial cells (fig. 38). ; 
Penial sete. A sae with two penial sete open jointly with each prostate. At 
least one of the sete is sculptured as shown in the figures 31 and 35, with a number 
of bristles, 12 or more. The smaller seta was broken in all the specimens, and I 
could not ascertain if it was sculptured or not. 
Nephridia. Benhamia nana belongs to a group in which the nephridia are 
arranged in three rows on either side of the median line. There is not a diffuse 
nephridic condition, but each nephridium is well developed, and upon the same 
principle as the mega-nephridia of Acanthodrilus. Nephridia a. >. are ventral and 
in front of setee 5 and 4, while the other nephridium c., is lateral and partly dorsal. 
The posterior nephridial ducts, from xvii to xviii, are superposed each on a large oval 
sac of coelomic cells, while those in front of the male-pore are not furnished with any 
coelomic mantle. Of the anterior nephridia those in the genital somites are some- 
what smaller than those in the vicinity of the pharynx, the increase in size forward 
being gradual. Blood capillaries are found in great numbers on all the nephridia, but 
Memorrs, Vou. II, 5. December 14, 1895. 
