. Zoology for high schools and colleges. Zoology. 203 insertion of the muscles it enlarges, but there is no true stomach; it is about twice the length of the body, and is bent and twisted on itself, ending dorsally in a vent marked by an external wart, on the anterior third of the body. Near this point is situated a pair of large, long, slightly twisted segmental organs(s)thefree ends of which flare slightly. The nervous system (n) forms an oesophageal ring, and from it passes a well- marked ventral single cord, from which at short intervals pass off small short lateral nerves. The v
. Zoology for high schools and colleges. Zoology. 203 insertion of the muscles it enlarges, but there is no true stomach; it is about twice the length of the body, and is bent and twisted on itself, ending dorsally in a vent marked by an external wart, on the anterior third of the body. Near this point is situated a pair of large, long, slightly twisted segmental organs(s)thefree ends of which flare slightly. The nervous system (n) forms an oesophageal ring, and from it passes a well- marked ventral single cord, from which at short intervals pass off small short lateral nerves. The vascular system is represented by a circular vessel lying next to the ner- vous oesophageal ring, sending branches into, or at least in communication with, the cavi- ties of the tentacles, and from the ring passing along and in- timately connected with the di- gestive tract, forming a ruffle- like organ {v), ending at a point nearly opposite the vent (a). Prof. Greef finds that the vas- cular system of Echhirus con- sists of two main vessels, i. e., a dorsal and a ventral vessel; the former extending along the alimentary canal, and sending a branch to the proboscis, where it divides into two branches, each uniting with the ventral vessel. The blood is pale yel- lowish, with corpuscles. The blood-system of the Gephyrea, then, is homologous with Fig. 140 —Anatomy of Phascolosoma Goutdii^ cut optiu, with the flapg pinned down, oe, oesophagus ; ar, two short muscles ; pr, two long ri^tractor mus- cles; w, next to a dark line the right side of the long oesopliagus indicatmg the w&ter-vascnlar tube ; w, nervous cord ; 5, segmental organs ; the long^ twi-ted intestine returns, ending at a Natural size.—Drawn by J. S. Kings- 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 Packard, A. S. (Alpheus Spring)
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Keywords: ., bookcentury1800, bookdecade1880, bookpublishe, booksubjectzoology
