Abstract
LIMULUS POLYPHEMUS.—A paper on the anatomy, histology, and embryology of Limulus polyphemus, by A. S. Packard, jun., M.D. (Anniversary Mem. Boston Soc. Nat. Hist. 1880), may be regarded as a continuation of the author's former series on the development and affinities of the king-crab. He discusses fully the question of the affinities of that puzzling animal, and combating the position of those zoologists who connect Limului with the Arachnida, he sums up the facts which point to the crustacean nature of Limuhis as follows:—(1) The nature of the branchiae, those of Limulus being developed in numerous plates overlapping each ether on the second abdominal limbs (those of the Eutrypterida being, according to H. Woodward, attached side by side like the teeth of a rake), while the mode of respiration is truly crustacean; (2) the resemblance of the cephalothorax of Limulus to that of Apus; (3) the general resemblance of the gnathopods to the feet of Nauplius or larva of the cirrhipedia and copepoda; (4) the digestive tract is homologous throughout with that of Crustacea, particularly the Deca-poda, there being no urinary tubes as in Tracheata; (5) the heart is on the crustacean type as much as on the tracheate type, and the internal reproductive organs (ovaries and testes) open externally, at the base of and in the limbs, much as in Crustacea. The paper is illustrated by seven plates showing the circulation of Limulus, sections of the adult and of embryos, and details of the structure of the eyes with comparison of these with those of Trilo-bites, with which group the author, as in his first mem Mr, allies the Merostomata.
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Biological Notes . Nature 24, 66 (1881). https://doi.org/10.1038/024066a0
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DOI: https://doi.org/10.1038/024066a0