162 CALIFORNIA ACADEMY OF SCIENCES. 
Ovipores are separate between somites xili/xiy, or slightly on the anterior part 
of xiv. 
Nephropores prominent in front of sete 1 and 2 in all somites posterior to xii. 
INTERIOR CHARACTERS. 
Body-wall. In somites x to xiv the body-wall is much thinner on the dorsal 
side of the body than on the ventral side. As Benham does not mention this peculi- 
arity in Sp. tamesis, and as I have not observed it in Sp. Smithi, I take it for granted 
that this character is peculiar to this species. The clitellum is complete, but much 
thinner on the ventral side between the sete, as shown by figure 119, which repre- 
sents the ventral body-wall in somite xix. It will be seen that the longitudinal muscular 
layer is several times thicker than the transverse layer. The strands are separated 
by irregular layers of granulated tissue of various thicknesses. The circular layer 
again consists of only one row of fascicles, each fascicle being tubular, and inclosing 
numerous irregularly distributed muscular fibers, strongly striate. When viewed in 
cross-section it becomes apparent that the strands of the longitudinal muscles are of 
varying thickness, the thicker ones being situated nearest the coelomic cavity, from 
there gradually decrease in size towards the circular muscles. 
Clitellar cells. The clitellar cells are especially interesting on account of their 
relationship to the cells of the tubercula pubertatis, which will be described later on. 
Figs, 107, 108 represent a longitudinal section of the body-wall in somites xxiii and xxiy. 
The muscular layers are much thinner, the clitellar cells are only developed in the 
vicinity of the prostates. Below the clitellar cells are seen long tubular cells, some- 
what like those of the tubercula pubertatis, and between them are seen, now and then 
(fig. 107 d.ch.), the deeply staining discharge chambers of the clitellar cells. The uni- 
cellular glands, which are here very irregular, are entirely confined to the zone 
surrounding the intersegmental grooves. In fig. 108 is seen a more magnified part 
of, the region close to the prostate. Only one unicellular gland, though of unusual 
size, is seen. It isastray one, as theyare rare in this particular zone. The structure 
of the clitellum of Sparganophilus has been well described by Benham in his paper 
on Sparganophilus tamesis, and I can only add a few points of interest. For studying 
the clitellar and tubereula pubertatis cells I have used principally the iron-lack 
Heidenhain process, but by adding a light tint of Ehrlich-Biondi to the ammonio- 
ferric-alum solution the most perfect differentiation may be had of the various clitellar 
elements. The clitellum in Sparganophilus contains the following various varieties 
of cells: 
1. Regular epidermal cells, secreting the cuticle, furnished with oval nuclei. 
Even on the fully developed clitellum of Sparganophilus Benhami they occur all 
around, both on dorsal and ventral sides. Their inner ends are drawn out into one or 
more threads, some of which extend to the innermost margin of the epidermis 
(fig. 103, 1). 
2. Unicellular goblet glands, entirely confined within the outer layer of the 
foregoing cells. They are very irregular as to size. These cells are the only ele- 
