PACIFIC COAST Oi-IGOCH^KTA. 173 



Betm strictly paired, sigmoid plain. The pair 1 and 2 is wanting in xvi. 



Spermathecal pores in ix in front of setas 1 and 2. 



Oviducal pores in xiv in front of setae 1 and 2. 



Spermndiical pores in the center of xvii, where otherwise would be the setai 

 1 and 2. A small copiilatory papilla around each male pore, but it is not connected 

 with a zone. No dorsal pores. 



INTERNAL CHARACTERS. 



Muscles. Numerous arciform muscles in the copulatory region, but especially 

 in xvii, connecting the copulatory papilhe with the body-wall in line with setse 3 and 4. 

 These arciform muscles are arranged in three distinct groups. The central group 

 which branches out fan-shaped from the inner surface of the copulatory papilhe, is by 

 far the largest, consisting of about 10 to 12 distinct fascicles. Anterior to this is 

 another group of 6 to 7 fascicles, and in the posterior part of the somite we find a 

 swollen group of about 5 fascicles. To what extent these vary as to numbers, etc., is 

 uncertain, but my observations in Fhwnicodriltis taste are that they are (piite constant, 

 and might be used as valuable characters in determining the species, as with a change 

 in the muscular strands is also connected one in the exterior copulatory zone. Between 

 xvii and xiii, as well as between xvii and xix we find several pair of arciform muscles 

 in each somite. 



Septal glaruh are well developed. The suprapharyngeal glands are very lono- 

 and extend far backwards. The septal glands in the following somites diminish 

 posteriorly. 



Spermathecm. One pair in ix open between viii/ix in front of setse 1 and 2. 

 Form sac-like, very thin walls, pellucid, outline smooth, without any warty diverticula. 

 No distinction between a muscular and glandular part. The size is large, about as 

 long as the somite is wide. 



Testes, ovaries and ciliated rosettes not characteristic. 



Ovisac. There is a median ovisac in xiii/xiv (fig. 157), consisting of a 

 pouching backwards of part of the septum. This is the only species in the tiiree 

 genera, Ocnerodrilus, Gordiodrilus and Phoenicodrihis, which ])ossesses an ovisac. 



Spermducts are of the same width throughout, without any muscular enlarge- 

 ment near the male pore. The two ducts run together, but their lumens are separate 

 until they reach the muscular atrium, where, just before they enter it, the two lumens 

 fuse into one (figs. 158, 15'J). 



Muscular atrium. As has already been stated the usual prostates in Ocnerodrilus 

 are replaced by a pair of muscular pouches, entirely covered up by the numerous 

 arciform muscles. There are no glandular cells, and these atria can best be compared 

 to the basal muscular |)ai-ts of the Ocnerodrilid prostate only they are very much 

 thicker, and consist entirely of muscular cells with the lumen in the body-wall lined 

 by columar epithelium. In the main pouch this epithelium consists of short cells with 

 round nuclei, around which extends a thin muscular layer, which becomes wider at 

 the base. This atrium is very short and cannot readily be seen when the opened 



