natural, history

The first obviously functional dorsal pore is On 12/13 (17 specimens, but 9 of whichhave a more or less porelike marking on 11/12), on 13/14 (2, but with a pore-like mar­...king on 12/13 in each case.)'. Clitellum, annular, is on xiv-xvi, intersegmental furrows,dorsal pores and setae unrecognizable.Quadrithecal, pores on 7/8-8/9, fairly widely separated, fairly large, crescentic slits,concave anteriorly with marked tumescence of anterior lip or of anterior wall of thepassage just within the parietes. The female pore (single) is median on 14 specimensbut its position (and number) uncertain on the other worms. Male pores are smallerthan the spennathecal but larger than the female. Each is usually on a small, slightlyraised porophore of about the same size as a genital marking, or on a flat or evenslightly depressed area that seems not be distinctly delimited.Genital markings are small, circular, with a greyish translucent central areadistinctly demarcated from an opaque rim which may not be as distinctly delimitedperipherally. The epidermis of the central area seems to have completely disappearedin some of the more macerated specimens, in which case there are visible several darkperforations in the muscle layers through which, presumably, ducts of a gland hadpassed.Unpaired, median markings are located as follows: presetal on xvii (19 specimens),xviii (21), xix (17), xx (5), xxi (2), xxiii (I), ix (16), x (13), xi (1), postsetal on xviii (4).Occasionally one of the markings is more or less completely doubled, double centersbut common rim, separate rims but in contact or almost so, once each on xvii, xviii,xix, ix and x. Additional markings are also in pairs, or with one of the pair lacking.The following were recognized (but others may have been overlooked because of thecondition): two markings just median to a male porophore, one pre- and one postsetal(II specimens). One marking in line with the male porophore and on or close to17/18 (9 specimens in one of which the marking is doubled). On or close to 18/19,or perhaps postsetal on xviii, and lateral to level of male pores (II specimens), on ornear 19/20 and on or lateral to level of male pores (I specimen). Additionally there isjust behind each male porophore a small transversely slit-like depression in which theepidermis is gr@y translucent but without any indication of a peripheral margin. Withstretching resulting from advanced maceration the slit disappears but the area oftranslucence is still obvious.Internal anatomy. Septa 8/9-9/10 are lacking, 10/11-12/13 apparently notespecially muscular. Intestinal origin in xv (7) but in three of the specimens this wasnot at first recognizable. Intestinal caeca, simple, are long enough to reach anteriorlyinto xix or xx or even xviii, and are filled, to the ends, with the same material as theintestine. The typhlosole is low but still definitely lamelliform, becoming translucentposteriorly and gradually disappearing from view, represented anterior to the caecalsegment by a much lower and more rounded ridge.The single heart of ix is on the left (4) or the right (3) side. Hearts of x are lacking(7), ofxi also (4). Those of xii-xiii are large (7) and probably latero-oesophageal. Dorsalportions of the right heart (I specimen) or of both right and left hearts (I) of xi arepresent, of the same appearance and nearly as large as in xii-xiii. However, the shortheart-like portion abruptly narrows to a thread which passes to (and apparently into)12