. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. CRVPTOCHITON STELLERI MIDD. 215 At the extreme lateral border of the percardium and about one fourth its greatest length from its anterior end the relatively large inner opening occurs (Fig. 2, r) and almost immediately leads into a flat disc-like cavity closely attached to the ventral pericar- dial wall. From the inner border of this flattened sac a slender delicate tube, usually almost invisible in preserved material, pro- ceeds forward and becomes continuous with the more dorsal tube of the glandular portion of the kidney
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. CRVPTOCHITON STELLERI MIDD. 215 At the extreme lateral border of the percardium and about one fourth its greatest length from its anterior end the relatively large inner opening occurs (Fig. 2, r) and almost immediately leads into a flat disc-like cavity closely attached to the ventral pericar- dial wall. From the inner border of this flattened sac a slender delicate tube, usually almost invisible in preserved material, pro- ceeds forward and becomes continuous with the more dorsal tube of the glandular portion of the kidney proper. This last- named section consists, as in chitons generally,of numerous highly branched lobules which extend ventrally some distance on the inner surface of the foot, dorsally to the valves of the shell and to the head cavity in front. In a number of species of chitons the outer limb of the excretory canal expands into a well defined reservoir (Nierensack), which is also supplied with glandular outgrowths. In some cases these reservoirs are of compara- tively large size and in a few cases they may extend close to the mid-line, but here, as in every species of chiton hitherto described, one kidney is wholly independent of the other. In Ciyptochiton, on the other hand, the reservoirs, that are probably distinct in very young specimens, unite in the mid-line and form, as Figs. I and 2 show a spacious chamber lying ventral to the anterior third of the pericardial cavity. In specimens one fourth the adult size, and occasionally in individuals of much greater length, there are slight indications of a median partition that may represent the line of fusion of the once independent divisions. Carefully removing the rectum and opening the ventral wall of this common reservoir the latter will be found to terminate posteriorly in two triangular diverticula, each of which communi- cates by means of a narrow slit immediately behind the trans-. Fig. I. Diagram illustrating the kidney o
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
