. Contribution to the natural history of the pearly nautilus. Nautilidae. 728 PROCHORDATA. The diagrams here reproduced are founded primarily upon conditions prevailing in the larva of Amphioxus, which are of the utmost complication as soon as one approaches. Fig. 17. Diagrams to elucidate some suggested comparisons between an Enteropneust (A), an Ascidian larva (B), and a Craniate embryo (C). A. p. proboscis; proboscis pore-canal opening close to the anterior neuropore which leads into the collar nerve-tube; epiphysial roots; s. stomochord; m. mouth; c. collar-region; g. gut;
. Contribution to the natural history of the pearly nautilus. Nautilidae. 728 PROCHORDATA. The diagrams here reproduced are founded primarily upon conditions prevailing in the larva of Amphioxus, which are of the utmost complication as soon as one approaches. Fig. 17. Diagrams to elucidate some suggested comparisons between an Enteropneust (A), an Ascidian larva (B), and a Craniate embryo (C). A. p. proboscis; proboscis pore-canal opening close to the anterior neuropore which leads into the collar nerve-tube; epiphysial roots; s. stomochord; m. mouth; c. collar-region; g. gut; t. trunk- region; dorsal nerve-tract; a. anus; py. pygochord. B. organ of fixation; e. endostyle; m. mouth; anterior neurenteric canal which, together with , subneural gland, constitutes the neuro-hypophysis; cerebral vesicle; sp. medullary tube communicating with the gut by means of posterior neurenteric canal; re. notochord. C. ep. pineal body or epiphysis cerebri; and fore-, mid-, and hind-brain; hy. hypophysis cerebri; th. thyroid gland ; other letters as above. them in a morphological spirit. In the Prochordata (including for the present occasion the Enteropneusta, Tunicata, and Cephalochorda) the three principal canal systems of the body, namely, coelomic, neural, and alimentary, open in various ways to the exterior in the anterior region, where they form an intricate association of apertures which I have formally designated as the anterior trematic complex. The following table will possibly be useful to future investigators who may venture to wrestle with this Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Willey, Arthur, b. 1867; Willey, Arthur, b. 1867. Zoological results based on material from New Britain, New Guinea, Loyalty Islands a
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