• WordNet 3.6
    • n Monotremata coextensive with the subclass Prototheria
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Webster's Revised Unabridged Dictionary
    • n. pl Monotremata (Zoöl) A subclass of Mammalia, having a cloaca in which the ducts of the urinary, genital, and alimentary systems terminate, as in birds. The female lays eggs like a bird. See Duck mole, under Duck, and Echidna.
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Century Dictionary and Cyclopedia
    • n monotremata In mammalogy, the lowest order of the class Mammalia, containing those mammals which have a single or common opening of the genital, urinary, and digestive organs, and are oviparous. The order coincides with the subclass Ornithodelphia, and also with Prototheria and Amasta; it is divided into two suborders, Tachyglossa and Platypoda, respectively constituted by the families Tachyglossidæ (or Echidnidæ) and Ornithorhynehidæ (or Platypodidæ). There are mammary glands, but no nipples. There is a common cloaca, into which empty the sperm-ducts, oviducts, and ureters, and which also receives the feces, as in birds; and the females lay eggs like those of reptiles. The testes, like the ovaries, remain abdominal. There is a peculiar T-shaped episternum or interclavicle, and the coracoid joins the sternum, as in birds. (See cut at interclavicle.) There are no true teeth. The very peculiar mammals which constitute this order are the duck-mole or duck-billed platypus, Ornithorhynchus paradoxus, and several species of so-called spiny ant-eaters, of the genera Echidna or Tachyglossus and Zoglossus or Acanthoglossus. See cuts under duckbill and Echidnidæ.
    • n monotremata In conchology, a division of geophilous pulmonate gastropods, having the external male and female orifices contiguous or common: opposed to Ditremata.
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Chambers's Twentieth Century Dictionary
    • Monotremata mon-ō-trem′a-ta the lowest order of Mammalia, having a single opening for the genital and digestive organs
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Webster's Revised Unabridged Dictionary
NL., fr. Gr. mo`nos single + hole
Chambers's Twentieth Century Dictionary
Gr. monos, alone, trēma, a hole.


In literature:

No doubt a slip of the pen for Monotremata.
"More Letters of Charles Darwin" by Charles Darwin
The Monotremata and Marsupialia have curious Y-shaped spleens.
"Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 8" by Various
The Monotremata are eminently interesting, as in several important points of structure they lead towards the class of reptiles.
"The Descent of Man and Selection in Relation to Sex, Vol. I (1st edition)" by Charles Darwin
It is much more nearly paralleled in the little group of Monotremata allied to the living Ornithorhynchus.
"Dragons of the Air" by H. G. Seeley
NIPPLES, absence of, in Monotremata, i.
"The Descent of Man and Selection in Relation to Sex" by Charles Darwin
The question is, What is the relation of these bonelets to the coracoid of the Monotremata and to the corresponding regions of reptiles?
"The Cambridge Natural History, Vol X., Mammalia" by Frank Evers Beddard