combining form of Gr. λεπτός fine, small, thin, delicate, used in many terms of Zoology and Botany: Leptocardian a. Zool. [Gr. καρδία heart], belonging to the Leptocardii, the lowest group of true vertebrates, having contractile pulsating sinuses instead of a heart; sb., a vertebrate belonging to this group (Cent. Dict., 1889). Leptocephalan, -cephalid Ichthyol. [Gr. κεφαλ-ή head], a fish of the family Leptocephalidæ. Leptocephalic a., having a narrow skull; exhibiting leptocephaly; Ichthyol., as the designation of certain flat-fish (cf. prec.). Leptocephaly, narrowness of skull. Leptodactyl Ornith. [Gr. δάκτυλος toe] a., having thin or slender toes; sb., a bird with slender toes. Leptodactylous a. [-OUS], = prec. a. Leptodermous a. Bot. [Gr. δέρμα skin], having thin skin, said of moss-capsules when pliable (Syd. Soc. Lex., 1888). Leptoglossal a. Zool. [Gr. γλῶσσα tongue], of or pertaining to the division Leptoglossa of lizards, having slender tongues (Cent. Dict.). Leptoglossate a., leptoglossal; sb., a lizard of this group (ibid.). ǁ Leptomeningitis Path., inflammation of the pia mater and the arachnoid (the leptomeninges). ǁ Leptophloem Bot. [see PHLOEM], in certain mosses (see quot.). Leptophyllous a. Bot. [Gr. φύλλον leaf], slender-leaved (Mayne, Expos. Lex., 1855). Leptoprosope [Gr. πρόσωπον face], narrowness of face; the condition of having a long narrow-faced skull (Cent. Dict.). Hence Leptoprosopic a., having a long narrow face. Leptorrhine a. [Gr. ῥῑν-, ῥίς nose], having a long narrow nose; having a nasal index of 47 or under; also Leptorrhinian, -rhinic adjs. Leptosperm [Gr. σπέρμα seed], a plant of the genus Leptospermum of myrtaceous shrubs (Cent. Dict.). Leptosporangiate a. Bot. [see SPORANGIUM], having sporangia that are developed from a single epidermic cell. ǁ Leptothrix [Gr. θρίξ hair], ‘a fungus belonging to the Order Schizomycetes, consisting of very thin and long, indistinctly segmented, straight threads’ (Syd. Soc. Lex.); also attrib. Leptoxylem Bot. [XYLEM], a structure in certain mosses (see quot.).
1842. Brande, Dict. Sci., etc., *Leptocephalans, Leptocephalidæ, the name of a family of fishes characterized by the smallness of the head, of which the genus Leptocephalus is the type.
1886. Pop. Sci. Monthly, XXIX. 114. Many young flat-fish … assume that peculiarly elongated and strange form known as *leptocephalic.
1882. Q. Rev., Jan., 251. These *Leptocephalids are small, narrow, elongate.
1864. Vogt’s Lect. Man, ii. 30. Platycephaly stands opposed to *leptocephaly, though connected with it by gradual transitions.
a. 1864. Hitchcock (cited in Worcester), *Leptodactyl … Leptodactylous.
1855. Mayne, Expos. Lex., Leptodactylus, *leptodactylous.
1866. A. Flint, Princ. Med. (1880), 693. Sometimes inflammation of the pia mater is denominated *leptomeningitis, in distinction from pachymeningitis which is inflammation of the dura mater.
1889. Bennett & Murray, Cryptog. Bot., 146. A *leptophloem or rudimentary phloem, in which the storing up and conduction of the food-material takes place.
1889. Garson, in Jrnl. Anthrop. Inst., XVIII. 23. The midfacial index … in the three Yasinese skulls … is very constant and averages 54·2, making them dolichofacial, or *leptoprosopic.
1880. Dawkins, Early Man, vii. 192. The *leptorhine rhinoceros.
1884. J. E. Lee, Romer’s Bone Caves Ojcow, 31. In both the Wierzchow skulls the nose is leptorrhine.
1878. Bartley, trans. Topinard’s Anthrop., II. ii. 257. The *leptorrhinians, with the nasal skeleton elongated.
1891. Athenæum, 25 July, 132/3. Dr. Topinard communicates documents on the nasal index of the living…. 491/2 per cent. … were leptorhinian … and 43 per cent. mesorhinian.
1887. Garnsey, Goebel’s Classif. Plants, 193. Two divisions of the Filicineae, the *Leptosporangiate and the Eusporangiate.
1877. Bennett, trans. Thomé’s Bot., 259. The forms known as Termo, Bacterium, Vibrio, Spirillum, *Leptothrix, &c.
1882. Pop. Sci. Monthly, XX. 718. Bacteria attached end to end in a string form filaments of leptothrix.
1885. Klein, Micro-Organisms, 89. Long leptothrix filaments composed of short joints.
1897. Allbutt’s Syst. Med., IV. 743. The leptothrix fungus and spores are almost invariably present in the concretions of tartar that gather round the teeth.
1889. Bennett & Murray, Cryptog. Bot., 146. A *leptoxylem or rudimentary xylem which serves for the conduction of the transpiration-current to the lower portion of the sporange furnished with stomates.
