. The Cambridge natural history. Zoology. VALVIFERA ASELLOTA I 27 of the mouth-parts, while the maxillipedee undergo an enlarge- ment, and are used for causing a current through the brood- ciiamber. Sub-Order 3. Valvifera. The Valvifera, illustrated by the Idotheidae and Arcturidae, are characterised by the uropods being turned back and expanded to form folding doors covering up the delicate pleopods, which are mostly respiratory in function, though the anterior pairs may serve as swim- ming organs. Arc- turns is a typically deep sea genus, many species, re- markably furnished with spinyproces
. The Cambridge natural history. Zoology. VALVIFERA ASELLOTA I 27 of the mouth-parts, while the maxillipedee undergo an enlarge- ment, and are used for causing a current through the brood- ciiamber. Sub-Order 3. Valvifera. The Valvifera, illustrated by the Idotheidae and Arcturidae, are characterised by the uropods being turned back and expanded to form folding doors covering up the delicate pleopods, which are mostly respiratory in function, though the anterior pairs may serve as swim- ming organs. Arc- turns is a typically deep sea genus, many species, re- markably furnished with spinyprocesses, having been taken by the Challenger in the southern hemi- sphere. The Ido- theidae are more lit- toral forms, several species of Idotliea being conunonly met with off the British coasts, oc- casionally penetrat- ing into brackish or even fresh water. Sub-Order 4. Asellota. In this group the abdominal segments are fused dorsally to form a shield-like caudal region ; the pleopods are respiratory in function and reduced in numbers, the first pair being often expanded and produced backwards to form an operculum covering the rest. Several of the Asellota are fresh-water, Aselhis aquaticvs. Fig. 83.—Ifunnopsis typica (Munnopsirlae), i, y. 2. A, 2nd antenna ; Ab, abdomen ; T, 5th thoracic appendage or 4th leg. (After Sars.). 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), Sir, 1862- ed; Shipley, A. E. (Arthur Everett), Sir, 1861-1927. ed. [London, Macmillan and Co. , Limited; New York, The Macmillan Company
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
