1(12 c;amfoknia acahk.my uk scjknces. 



PLATE XXXV. 



PONTODRILUS MICHAELSENI. 



40. Cross-Beotion through somite xvii of a matiire specimen Hhowiug the development of the clilellar cells on the 



dorsal and lateral sides of the clitellum. i\ cl. ventral termini of the clitellar cells. il. i\ dorsal vessel. 

 ». I. sacculated intestine. neph. nephridinm. 'jl. i>r. glandular part of prostate. /ir. m. muscular part of 

 prostate. m. muscles connecting the prostate with the body-wall. I. m. transverse muscles. /. m. longi- 

 tudinal muscles, rl. clitellar colls, c. cl. ventral termini of the clitellar region. 



41. Cross-section through a strongly contracted, fully matured specimen, through somite xviii, showing the copula- 



tory cushions as fully developed, as well as the clitellar cells on the ventral side. Unfortunately the only fully 

 developed specimen at m_v disposal had been badlj' contracted, hence the cells appear smaller than they wnuld 

 have done in properly prepared specimens, c. c. copnlatory cushions, a. m. areiform or fan-shaped muscu- 

 lar strands, which contract the copnlatory region, i. t. m. interior transverse muscular strand, ending 

 respectively in the copnlatory cushions and in the projecting ventral lubes of the br)dy. Other letters as in 

 the last four figures. 



4'J. The body-wall viewed from the inner side of somites xvii, xviii and xix, showing the genital region of the loft 

 side. ///•. m. prostate muscles connecting this organ with the body-wall. n. m. areiform muscles connecting 

 the copnlatory cushion with the upper body-wall. c. r. copnlatory cushion, .s/i. m. muscles connecting the 

 body-wall with the prostate at the junction with the spcrmduct. n/i.il. spermduct. 1 anil .^ ». first and 

 second seta. v. c. ventral nerve cord. <ll- pr. glandular prostate, m. pr. muscular prostate, s. in. smaller 

 muscles, fan-like arranged, confined entirely to the copulatory cushion, sp. il. p. spermidncal pore overlaid 

 by muscles, n. septa. 



i'.i. A somewhat diagonal longitudinal section through the body-wiiil and copnlatory cushion in somite xviii. The 

 section is parallel with the muscular fan of areiform muscles, passing through the copulatory cushion near 

 but not through the body-wall. Illustrating the arrangement of the muscular strands around the prostate iu 

 the vicinity of the male pore. The letters indicate the same as iu the preceding figure. 



44. A longitudinal section through the cojuilatory cushion and the body-wall, the section being almost vertical. 



pr. prostate, just leaving the areiform nmscles, and inimidiately before bending down towards the prostate 

 pore. 711. muscles connecting the prostate with the body-wall. n. m. the entrance of the areiform muscles 

 into the copulatory cushion. 



45. A horizontal section of ihe body through somite xviii and the copulatory cushions, showing their size and 



position, etc. 



