. Bulletin - United States National Museum. Science. 354 BULLETIN 140, UNITED STATES NATIONAL MUSEUM in species of Tetrameres. Cuticle transparent, finely striated trans- versely, often projecting as the coils tighten. Anterior and posterior extremities projecting to varying degree, never to a length of more than half the diameter of the worm, and sometimes retracted into the center of the coil. Buccal capsule dome-shaped. Esophagus long. Intestine a black irregular tract, twisting with the coils. Posterior extremity (fig. 416 /) sharply pointed; anus 450/*, vulva 900/x from the posterior end,
. Bulletin - United States National Museum. Science. 354 BULLETIN 140, UNITED STATES NATIONAL MUSEUM in species of Tetrameres. Cuticle transparent, finely striated trans- versely, often projecting as the coils tighten. Anterior and posterior extremities projecting to varying degree, never to a length of more than half the diameter of the worm, and sometimes retracted into the center of the coil. Buccal capsule dome-shaped. Esophagus long. Intestine a black irregular tract, twisting with the coils. Posterior extremity (fig. 416 /) sharply pointed; anus 450/*, vulva 900/x from the posterior end, cuticle thickened into a rounded swell- ing between the two openings. Eggs 40 to 45ju, long by 20 to 25/a wide, containing coiled embryos when mature; some eggs show peculiar unilateral bib attached to outside of shell (fig. 416 g).. Fig. 416.—Microtetrameres contorta. a and b, Males ; c, yodngest FEMALE, SHOWING TENDENCY TO COIL ; d AND e, MATURE FEMALES ; f, TAIL OF FEMALE ; (J, OVA, UNILATERAL BIB REPRESENTED ON ONE ; h, MATURE FEMALE, SHOWING COURSE OF ESOPHAGUS AND INTESTINE ; X, HALF GROWN FEMALE, COILED IN ONE PLANE ONLY. AFTER WEIDMAN, 1913. j, Wax reconstruction of female. After Weidman, 1923 Weidman made a very careful study of females of varying ages (fig. 416 c to e and h to j); one of the wax reconstructions made by him is shown in figure 416 j. He concludes that the propensity to coil is of very early development. The arrangement of coils is not constant, being either clockwise or contraclockwise. Head always bent dorsally; posterior extremity always twists suddenly in direc- tion opposite to that of anterior coils. With egg production the coils broaden out so that the mass appears globular. Life history.—Probably similar in a general way to that of T. flssispina (see p. 313). Distribution.—North America (United States (Pennsylvania (Zoological Garden, Philadelphia)).. Please note that these images are extracted from scanned page images that may have been d
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Keywords: ., bookauthorun, bookcentury1800, bookdecade1870, booksubjectscience
