acentric (asentrik)

[ pound adj. termination, as in herb - ace us, ros ace us, gall in - ace us, cret-ace us, test-ace us, etc.: see the corresponding E. forms.] An adjective suffix, as in herbaceous, cretaceous, etc., used especially in botany and zoölogy, forming English adjectives to accord with New Latin nouns in- aceæ, -ace a (which see), as rosaceous, lilia ceo us, cetaceous, crustaceous, etc. acephal (as'e-fal), n. One of the Acephala . Acephala (a-sef'a-la), n . pl . [NL., ἀκέφαλος , headle : see acephalus .] 1. A term introduced by Cuvier into systematic zoölogy, and applied by him as a cla name to a combination of the conchiferous lamellibranch i ate mollusks and the tunicates. Later writers apply it to the lamellibranch i ate mollusks alone, which constitute a natural cla , distinguished by Lamarck as the Conch if era. All the ordinary bivalves belong to this cla . The Acephala or Acéphales of Cuvier were at first (1789) the third order of Mollusca , and included cirripeds, tunicates, and brachiopods with ordinary bivalve mollusks, being thus equivalent to Cirriped i a , Tunic at a , and Conchi fer a of Lamarck. In 1804 Cuvier excluded the cirripeds and brachiopods, and made Acephala a cla of Mollusca . In the "Règne Animal" (1817-1829) Acephala are Cuvier's fourth cla of Mollusca , with two orders, Acephala testacea, or shelled acephals, the ordinary bivalve mollusks, and Acephala nuda , or shell-le acephals, the tunicates. Acephala 2. Same as A crania.-3. In Latreille's system of cla ification (1795), one of seven orders of the Linnean Aptera, containing the spiders, etc., corresponding to the A rach nides pal pistes of Lamarck, and synonymous with Arachnid a. 4. In Haeckel's cla ification, a group of Mol lusca composed of the Spirobranchia, or Brachi opoda, and the Lamellibranch i a. Acephalæa (a-sef-a-lē'ä), n..pl. [NL., a modification of Acephala, after Gr. κεφάλαιος (neut. pl. κεφάλαια ), belonging to the head, ond order of Mollusca, the Acephala of Cuvier, 1789, in cluding cirripeds, tunicates, and brachiopods with ordinary bivalve mollusks. In 1809 Lamarck excluded the cirripeds, and in 1812 he excluded the tunicates, making Acephalora a cla of Evertebrata, with two orders, Mono myaria and Dimyaria. See Conch if era.