PACIFIC COAST OLIGOCH^IiTA. 165 



posed of two distinct lobes of about equal size, one situated closely posterior to the 

 other. This is also the structure of the septal glands in iv and v, but the one in vi is 

 solid, consisting of only one lobe, when viewed in longitudinal section. The main 

 lobes are situated on the .';anie longitudinal muscular band, witii their discharge ducts 

 running forwards into the pharyngeal cavity, [n each of the three somites there are 

 two distinct glands on either side of the median line. One larger supraintestinal 

 consisting of three parts extending laterally, and one smaller subintestinal. These 

 latter ones also open into the pharynx, but into its ventral side, the pharynx 

 thus being partially developed even on the ventral side. The discharge tubes and 

 chambers are very large, and the latter occupy more than one-half the width of the 

 pharyngeal wall. They stand very close together, and are all of about tiie same height 

 and form (fig. 112). The dorsal wall of the pharynx is much thicker and denser 

 than the ventral one, and the discharge chambers stand closer and are of more uni- 

 form size, more tubular. The discharge chambers on the ventral side are thicker, 

 more pear-shaped and much fewer in number. Fig. 112 represents the lining of 

 the dorsal wall of the pharynx; fig. 115 the ventral wall of the same, and fig. 114 

 the wall next posterior to the main dorsal section. 



(Esophagus and intestine. The description given by Benham of the histology 

 of the intestine of Sp. tamesis may in the main points be applied to this species. 

 The oesophagus is cylindrical with parallel sides and slightly nipped by the septa. It 

 is sparsely covered by chloragogen cells, which latter are more numerous on the 

 intestine. The ciliie of the inner epithelium are much longer in the oesophagus, 

 and so are the epithelial cells themselves. Seen in longitudinal section (fig. 110) 

 we find that the transverse muscles surrounding the eesophagus are more numei'ousand 

 present in several rows, while in the intestine they are few and far between, and 

 arranged only in one row. There is thus a distant approach to a gizzard in the 

 oesophagus. The longitudinal muscular layer is reduced everywhere in the intestine 

 to a single strand, but in the resophogus it is double, sending out strands to the septa 

 and to the mesenteric sac. 



Blood sinus. Both Benham and Smith have shown the existence of a conti- 

 nuous blood sinus in the intestine of the species described by them. In the oesophagus 

 of our present species we find only a vascular network and confluent smaller lacunes, 

 but in the intestine proper we meet with a continuous blood sinus all around the 

 epithelial cells. The radiated appearance of the blood in the sinus, as well as in the 

 other vessels, must as Benham suggested be due to the crystalization of htematine. In 

 8p. Benhami and Sp. Smithi these crystals are so many and so heavy that they invari- 

 ably destroyed the edge of the microtome knife and made sectioning most difficult. 

 But the crystalization presents some peculiarities, and in places appears as if there 

 was a mass of radiating fibers always from the side nearest the center of the body 

 radiating towards the periphery, but never the contrary. In *S'/;. Benluimi these crystals 

 are much more slender than in -S'^;. Smithi. In the latter species their nature is not 

 to be doubted. They are also found in the hearts, but more rarely in the main longi- 

 tudinal vessels. 



