GLOSS AKY. 491 



Infusoria (Lat. infusum, an infusion). A class of Protozoa, so called be- 

 cause they are often developed in organic infusions. 



Inoperculata (Lat. in, without ; opercichcm, a lid). The division of pul- 

 luonate Gasteropoda in which there is no shelly or horny plate (operculum) 

 by wliicli the shell is closed when the animal is withdrawn within it. 



Insecta (Lat. inseco, I cut into). The class of Articulate animals commonly 

 known as Insects. 



Insectivoba (Lat. inscctum, an insect ; voro, I devour). An order of 

 Mammals. 



Insectivorous. Living upon Insects. 



Insessoues (Lat. inscdeo, I sit upon). The order of the Perching Birds, often 

 called Passer cs. 



Interambulacra. The rows of plates in an Echinoderm which are not per- 

 forated for the emission of the "tube-feet." 



Intermaxill^, or Pe^maxill^. The two bones which are situated between 

 the two superior maxillas in Vertehrata. In man, and some monkeys, the 

 praemaxillse anchjdose with the maxillse, so as to be irrecognisable in the 

 adult. 



Inveetebrata (Lat. in, without ; vertebra, a bone of the back). Animals 

 without a spinal column or backbone. 



Ischium (Gr. iscMon, the hip). One of the bones of the pelvic arch in Verte- 

 brates. 



IsopoDA (Gr. isos, equal ; 2^odes, feet). An order of Crustacea in which the 

 feet are like one another and equal. 



Jugular (Lat. juguhim, the throat). Connected with, or placed upon, the 

 throat. Applied to the ventral fins of fishes when they are placed beneath 

 or in advance of the pectorals. 



Kainozoic (Gr. Minos, recent; zoe, life). The Tertiary period in Geologj', 



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. 

 Kerato-sa. 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. 



Labteinthodontia (Gr. lahurinthos, 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 Eep)tiliM comprising the 

 Lizards and Slow-worms. 



L^MODIPODA (Gr. laimos, throat ; dis, twice ; podcs, feet). An order of Crus- 

 tacea, 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 MoUusca, comprising the ordinary Bivalves, characterised by the posses- 

 sion of lamellar gills. 



