A List Of The Protozoa And Rotifera Found In The Illinois River And Adjacent Lakes At Havana Ill

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1898 edition. Excerpt: ...have the body covered with a very thin chitinous external cuticula, while a great many have a hard, inflexible carapace or lorica. A number of species inhabit tubes, which they either secrete or build up from surrounding debris and pellets of excreta. Members of this group are readily recognized by the presence of tbe mastax, a more or less irregularly three-lobed muscular organ, containing the teeth, jaws, or trophi, as they are variously called. These are composed of chitin, are hard and durable, and are true masticatory organs. Although some of the rotifers have no cilia, all of them agree in having a mastax and trophi, and as these structures are peculiar to the Rotifera they afford a ready means of identification. The mastax is usually situated in the anterior part of the body, just behind the buccal orifice or lips, and a short oesophagus connects it with a large stomach lying in the posterior dorsal part of the animal. Many rotifers have the power of protruding the tropin through the buccal orifice, and they may often be found nibbling at algae and other aquatic plants. Although the trophi are used by many rotifers to crush their food, there are some large forms, like Asplanchna, that swallow their food entire, as is shown by the uninjured rotifers, protozoans, and algae found in their stomachs. The chitinous jaws or trophi (Fig. 3) consist typically of two hammer-like lateral parts, the mallei, bearing one to seven comb-like apical teeth, and working upon the two halves of a divided central part, the incus. The mallei are usually separable into an apical part bearing the teeth, the uncus, and a basal part, the manubrium. The two divisions of the incus are the rami and its basal projection is the fulcrum. These inner and outer...

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