. The Cambridge natural history. Zoology. CLYPEASTROIDEA 547 suckers, but the first variety are much larger than the second; they possess a flattened lobed base, and are connected with the ampulla by a double canal. They issue only from the double pores which form the petal. The locomotor tube-feet are small and cylindrical; they are, as already mentioned, scattered over the whole upper surface of the test, penetrating both ambulacral and interambulacral plates, but all are connected by transverse canals with the radial canals of the water-vascular system. On the under surface they are confine
. The Cambridge natural history. Zoology. CLYPEASTROIDEA 547 suckers, but the first variety are much larger than the second; they possess a flattened lobed base, and are connected with the ampulla by a double canal. They issue only from the double pores which form the petal. The locomotor tube-feet are small and cylindrical; they are, as already mentioned, scattered over the whole upper surface of the test, penetrating both ambulacral and interambulacral plates, but all are connected by transverse canals with the radial canals of the water-vascular system. On the under surface they are confined to the neighbourhood of Fig. â 2i4.âDissection of JEchinarachnius paniia. x 1. Tlie oesophagus has been cut through and moved to one side so as to ex- pose Aristotle's lantern. The aboral part of the test lias been re- in o v e d. gon. Genital organ ; int, intestine ; imtsc, transverse muscle connecting jaws of adjacent inter- radii ; red, rec- tum ; siph, siphon; 5^, reel the ambulacral grooves, which have nothing to do with the ambulacral grooves of an Asteroid, but are due to secondary localisations of the tube-feet, which are here also connected in each radius with a single radial canal. The appearance of a living Uchinarachnius covered with a veritable forest of short brown tube-feet is very striking.^ The condition of the water-vascular system is to be explained entirely by the peculiar environment of the animal. The demand for specialised respiratory organs is brought about by the habit of livino- half buried in the sand. Under these circumstances the strain of supplying the needful oxygen is thrown on the 1 These statements are based on the author's observations of the animal in the Bay of Fundy in 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 Harmer, S. F. (Sidney Frederic), S
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
