162 CALIFORNIA ACADEMY OF SCIENCES. 



Ovipores are separate between somites xiii/xiv, or slightly on the anterior part 

 of xiv. 



Nei)hropores prominent in front of sette 1 and 2 in all somites posterior to xii. 



INTERIOR CHARACTERS. 



Body-v:ali. 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. tnmesis, and as I have not observed it in Sj). Stnithi, 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 setre, as shown b_y 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 celh. 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 bod3^-wall in somites xxiii and xxiv. 

 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. 101 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. Jn fig. 108 is seen a more magnified part 

 of the region clo.se to the prostate. Only one unicellular gland, though of unusual 

 size, is seen. It is a stray one, as they are rare in this particular zone. The structure 

 of the clitellum of Sparganophilus has been well described by Benham in his paper 

 on Sparganophilus tameais, and I can only add a few points of interest. For studying 

 the clitellar and tubercula pubertatis cells I have used principally the iron-lack 

 Heidenhain process, but by adding a light tint of Ehrlich-Biondi to the amraonio- 

 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 Spfirganojjhilus 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- 



