290 Transactions. — Zoology. 



segment are in line with ab, but the male pore is in line with b. 

 Copulatory tubercles are variously developed, but in all the 

 mature specimens there are paired oval post-chaetal glands on 

 segments 10 and 11 in line with ab. Some individuals have 

 others on segment 9 and even on the 8th as well. In a single 

 case, similarly paired papillae occur on segments 19 and 20 as well 

 as on the two anterior segments, and all are in the same relative 

 position on the segment, and have the same form — viz., trans- 

 versely oval, with a slight depression— giving the impression of a 

 sucker. 



Spermathecal pores : Three pairs, at the anterior margin of 

 segments 7, 8, and 9, in line with b. Nephridiopores also in 

 line with b. 



Internal Anatomy. — The six septa behind segments 8-13 are 

 stout. The dorsal vessel is single ; last heart in segment 12. 

 The worm is meganephric. 



Alimentary Tract. — A very small gizzard occupies the 5th 

 segment. A large lobulated and highly vascular salivary gland 

 lies on each side of the pharynx. The oesophagus is distinctly 

 dilated in the 13th segment to form a spherical sac, the lining of 

 which has the general villous structure of a gland, though the 

 lateral region is not constricted from the axial oesophagus. 



In segments 14-17 the gut is narrow, with a yellowish wall ; 

 in the 18th it suddenly dilates to form the thin- walled intestine. 



Reproductive System. — Three pairs of sperm-sacs occupy 

 segments 9, 11, and 12. The spermiducal (prostate) glands are 

 long, tubular, and undulating: each extends through the five 

 segments 17 to 21 inclusive. The short muscular duct is con- 

 fined to segment 17. The sacs of penial chaetae are also long. 

 On the removal of the arcuate muscles from segments 16, 17, 

 and 18, the two sperm-ducts on each side are readily seen on 

 the body-wall, and can be traced backwards outside the prostate 

 duct, where they bend mesially behind it and the penial sac to 

 open to the exterior. 



The penial chaeta (Plate XIV., fig. 6) is long, delicate, and 

 curved rather abruptly near the tip, which is slightly re- 

 curved. 



The only " ornamentation " is in the form of a few scattered 

 minute serrated markings some little distance below the tip. 



The three pairs of spermathecae are in segments 7, 8, and 9 

 (and in one specimen from Adam Island there are three on the 

 left side but four on the right). These increase in size back- 

 wards, and the diverticulum becomes relatively longer. Each 

 spermatheca (Plate XIV., fig. 2) consists of a large somewhat 

 ovoid sac with a short wide duct, into which opens a curved 

 cylindrical diverticulum. This, in mature forms, is longer than 



