Invertebrata

(Lat. in, without; vertebra, a bone of the back). Animals without a spinal column or backbone.

Ischium

(Gr. ischion, the hip). One of the bones of the pelvic arch in Vertebrates.

Isopoda

(Gr. isos, equal; podes, feet). An order of Crustacea in which the feet are all like one another and equal.

Jugular

(Lat. jugulum, the throat). Connected with, or placed upon, the throat. Applied to the ventral fins of fishes when they are placed beneath or m advance of the pectorals.

Kainozoic

(Gr. kainos, recent; zoe, life). The Tertiary period in Geology, comprising those formations in which the organic remains approximate more or less closely to the existing fauna and flora. Keratode (Gr. keras, horn ; eidos, form). The horny substance of which the skeleton of many Sponges is made up. Keratosa. The division of Sponges in which the skeleton is composed of keratode.

Labium

(Lat. for lip). Restricted to the lower lip of Articulate animals.

Labrum

(Lat. for lip). Restricted to the upper lip of Articulate animals.

Labyrinthodontia

(Gr. laburinthos, a labyrinth; odous, tooth). An extinct order of Amphibia, so called from the complex microscopic structure of the teeth.

Lacertilia

(Lat. lacerta, a lizard). An order of Reptilia comprising the Lizards and Slow-worms.

LAEMODIPODA

(Gr. laimos, throat; dis, twice; podes, feet). An order of Crustacea, so called because they have two feet placed far forwards, as it were under the throat.

Lamellibranchiata

(Lat. lamella, a plate; Gr. bragchia, gill). The class of Mollusca, comprising the ordinary bivalves, characterised by the possession of lamellar gills.

Lamellirostres

(Lat. lamella, a plate; rostrum, beak). The flat - billed Swimming Birds (Natatores), such as Ducks, Geese, Swans, etc.

Larva

(Lat. a mask). The insect in its first stage after its emergence from the egg, when it is usually very different from the adult.

Larynx

The upper part of the windpipe, forming a cavity with appropriate muscles and cartilages, situated beneath the hyoid bone, and concerned in Mammals in the production of vocal sounds.

Lenticular

(Lat. lens, a bean). Shaped like a biconvex lens.

Lepidoptera

(Gr. lepis, a scale; pteron, a wing). An order of Insects, comprising Butterflies and Moths, characterised by possessing four wings which are usually covered with minute scales.

Lepidota

(Gr. lepis, a scale). Formerly applied to the order Dipnoi, containing the Mud-fishes (Lepidosiren).

Leptocardia

(Gr leptos, slender, small; cardia, heart). The name given by Muller to the order of Fishes comprising the Lancelet, now called Pharyn-gobranchii.

Ligamentum NUCHAE

(Lat. nucha, the nape of the neck). The band of elastic fibres by which the weight of the head in Mammalia is supported.