PACIFIC COAST OLIGOCHJETA. 137 



INTERIOR CHARACTERS. 



Gizzards, two in vii and viii. 



Calciftrous diverticula. Three pairs in xv, xvi and xvii. 



Sacculated intestine commences in xviii. 



I'yphlosole present. 



Prostates slender, confined each to one somite. 



Spermathecce. The apical part a trifle smaller than the basal. Both parts 

 much flattened. A very small diverticulum pointing forwards. 



Nephridia in four rows on either side of the median line. The posterior ne- 

 phridia with cojlomic glanthilar mantle. Nephridia in each somite of about equal 

 size. Nephridia d and d about equidistant as a and >i. The most ventral part of 

 nephridium a not covered by the mantle. The clitellar nephridia larger than those 

 anterior to clitellum. 



DETAILED DESCRIPTION. 



Size. The specimens had been slowly killed and extended before hardening. 

 All the specimens were curved backwards, thus with the dorsal line on the inner 

 margin of the crescent, causing the male pores to be situated at the greatest bend on 

 the outer margin of the crescent. Most terricolpe curve the opposite way. 



Shape of segments. The first ten somites are very nearly of the same diameter 

 in the direction from head to tail. Boraites xi and xii are slightly narrower. The 

 clitellum which comprises somites xiii to xx shows plainly the intersegmental grooves. 

 The posterior somites are of a somewhat shorter diameter than xi and xii. All the 

 anterior somites including the most posterior ones of the cliteUum are sculptured by 

 longitudinal furrows running in the diameter from head to tail. This corrugation is 

 seen all around the body, and gives the anterior part of the worm a very marked 

 appearance. The posterior somites show a fainter corrugation. All somites are 

 3-ringed, except those of the clitellum. 



Prostomium is long and pointed and slightly curved upwards (figs. 57 and 58) 

 and is a trifle longer than somite ii. In all the specimens but one, somite i, was nearly 

 entirely retracted in the buccal cavity, and when viewed from the exterior only a 

 short portion of its dorsal part could be seen (fig. 58) and the prostomium appeared 

 as if projecting from somite ii. One specimen had somite i extended as figured 

 in fig. 59. Dr. Michaelsen has remarked a somewhat similar retraction of somite i in 

 B. kafuruensis. Sperraathecal pores as usual, vii-viii and viii-ix. 



Clitellum is narrower than the surrounding somites. It is strongly corrugated, 

 especially at the anterior and posterior margins. The prostate pores are, as usual, in 

 xvii and xix. The exterior part of the genital region is very characteristic. In 

 young specimens the two prostate pores are connected by a deep furrow in the 

 center of which is seen the slight depression for the male pore. In the two fully 

 adult specimens, however, the two anterior prostate pores were each situated on a 

 very large globular papilla, surrounded by a deep fossa; while no such papilla and 

 fossa characterized the posterior pair of prostate pores. In fact, these posterior pores 



