410 PROCEEDINGS OF THE NATIONAIj MUSEUM vol.85 



X — postsetal, both sides, In ab; xi — presetal pair in aa; xii — presetal, just to 

 left of midventral line ; xiii — presetal, both sides, in aa. 

 7. No genital markings. 



InterTidl anatomy. — Septa 5/6-8/9 are thickly muscular; 9/10 thin 

 and displaced posteriorly. 



The last pair of hearts is in ix. There is a band of opaque material 

 on each side of the dorsal blood vessel. 



The gizzards are three in xii-xiv (8 specimens). 



The testis sacs are usually flattened laterally and nearly fill the 

 available space in segments ix and x. The vas deferens is short, 

 rather thick relative to the size of the worm, and passes into the pros- 

 tate mesially without first passing into the parietes. The prostates are 

 flattened disks of circular outline, sessile on the parietes. The cen- 

 tral body is tiny, ovoidal, the more pointed end within the parietes- 



Segment xi is reduced to a closcd-off ovarian chamber of horseshoe 

 shape. The ovisacs are laterally flattened and confined to xii in the 

 clitellate specimen. In other worms the ovisacs are slenderer and 

 also confined to xii. A posteriorly elongated appendix such as char- 

 acterizes D. japonica is lacking. 



The spermathecal atrium is finger-shaped, erect on the posterior face 

 of 7/8. The spermathecal duct (7-9 mm long) passes into the atrium 

 near the ental end of the latter but runs ventrally in the atrial wall for 

 a short distance before opening into the atrial lumen. 



Remarks. — D. grahami is distinguished from D. japonica (Michael- 

 sen, 1892) as follows: Location of the spermathecal pores in mid he 

 rather than in or just median to c,- direct entrance of the vas deferens 

 into the prostate (rather than first passing into the parietes) ; pros- 

 tates disk-shaped and sessile on the parietes (rather than erect or 

 vertical and columnar to club-shaped) ; the very small, ovoidal, cen- 

 tral body of the prostate with the pointed end buried in the parietes 

 (rather than the elongate digitiform central body nearly 1 mm in 

 length) ; absence of an elongate rodlike appendix on the ovisacs. One 

 of the types is clitellate, hence fully mature, and presumably would 

 have had ovisac appendages if these structures are normally present 

 in this species. (In contrast, the rodlike appendices of the ovisacs are 

 recognizable even in juvenile specimens of japonica.) The exact mor- 

 phological location of the male pores was not determined, but the 

 pores are in line with 10/11, though the latter is not recognizable across 

 the male porophores. If the male pores are to be placed on 10/11 or 

 the site of 10/11 this will be still another distinction Irom japonica in 

 which the pores are quite definitely segmental, postsetal on x. 



Chen (1936, p. 291) maintains that the types of grahami are identi- 

 cal with japonica. Chen's notes on grahamii appear to be a confused 

 composite of observations made on specimens of both grahatni and 



