798 



OBUMBRAST. When the scutellum of an 

 insect overhangs the rnetathorax. 



OBVERSE. When an object is viewed with 

 its head towards you. 



OCCIPUT. That part of the skull which forms 

 the hind part of the head. 



OCELLATED. A term applied to eye-like 

 spots ; formed with the figures of little 

 eyes. 



OCELLUS. An eye-like spot in the wings of 

 many Lepidoptera, and consisting of an- 

 nul i of different colours, inclosing a central 

 spot or pupil. Blind Ocellus is one without 

 the pupil. Spurious Ocellus; a circular 

 spot without any defined iris or pupil. 

 Simple Ocellus ; when the ocellus consists 

 only of iris and pupil. Compound Ocellus ; 

 when it consists of three or more circles. 

 Nictitant Ocellus; when the ocellus in- 

 cludes a tumular spot of a different colour. 

 Fenestrate Ocellus; when an ocell\:s has a 

 transparent spot. Dioptrate Ocellus; a 

 fenestrate ocellus divided by a transverse 

 line. Double Ocellus ; when two ocelli are 

 included in the same circle or spot ; and 

 when such ocelli join each other they are 

 termed twin ocelli. Scsguialterous Ocellus; 

 an ocellus with a smaller near it. The 

 simple eyes of insects are small, transparent, 

 semi-globular lenses, generally three in 

 number, and arranged in a triangle on the 

 crown of the head. Though their use has 

 never been satisfactorily proved, enough 

 has been ascertained for Entomologists to 

 agree in considering them organs of vision. 

 The eyes of larva?, spiders, and some other 

 annulosa are simple ocelli, arranged in 

 groups. They are also called stcmmata. 



OCIIRACEOUS. Of a dull brownish yellow 

 colour ; approaching to the colour of ochre. 



OCTODENTATE. Having eight teeth. 



OCTOFID. In Entomology, separated into 

 eight segments. 



OCTONOCULAR. Having eight eyes. 



OCTOPOD. Having eight legs. 



OCTORADIATED. Having eight rays. 



OCULI (oculus. ) The eyes of insects are gene- 

 rally composite, i. e. formed of facets or mi- 

 nute lenses, which are hexagonal, and vary 

 from 50 to 20,000 in a single eye ; every 

 one of them receiving the image of an 

 object, and appearing to correspond with 

 the crystalline lens of the human eye. 



OCULIFORM. Shaped like the eye. 



ODORIFEROUS. Diffusing fragrance. 



CEsoPHAGEAL. Pertaining to the gullet. 



(ESOPHAGUS. The anterior extremity of the 

 alimentary canal ; the gullet. 



OFFICINAL. Pertaining k to drugs, perfumes, 

 &c., usually kept in apothecaries' shops. 



OLEAGINOUS. Unctuous ; having the quali- 

 ties of oil. 



OLFACTORY. Relating to the sense of smell- 

 ing ; as, olfactory nerves. 



OLIVACEOUS. Dull olive green, or green 

 tinged with brown. 



OLIVE. A brownish green, the colour of 

 olives. 



OMNIGENOUS. Consisting of all kinds. 



OMNIVOROUS. Feeding indiscriminately or 

 subsisting on all kinds of food. 



O.NYCHOTENTHIS. The genus of calamaries 

 armed with hooks or claws. 



&$$ gutty. 



OOLITE. Egg-stone ; an extensive group of 

 secondary limestones composed of rounded 

 particles, like the roe or eggs of a fish. 



OPALESCENT. Reflecting a coloured lustre 

 from a single spot. 



OPALINE. A bluish white reflecting the 

 splendour of the opal. 



OPAQUE. Impervious to the rays of light ; 

 not transparent ; a surface which does not 

 reflect the rays of light at all. 



OPERCULATK. When the eyes of insects are 

 covered by an operculum. 



OPERCULATED. Furnished with a lid or 

 cover. 



OPERCULIFORM. Having the form of a lid 

 or cover. 



OPEHCULUM. A lid or cover ; applied to the 

 horny plate which closes certain univalve 

 shells ; also to the covering of the gills in 

 fish. 



OPHIDIAN. Resembling or pertaining to 

 serpents ; designating an order of verte- 

 >rate animals destitute of feet and fins. 



OPIIIOLOGIST. A person versed in ophiology, 

 or the natural history of serpents. 



OPHIOLOGY. That part of Natural History 

 which treats of serpents. 



OPHIOMORPHOUS. Having the form of a ser- 

 pent. 



OPHIOPHAGOUS. Eating or feeding on ser- 

 pents. 



ORANGE. A colour composed of equal parts 

 of red and yellow. 



ORBICULAR. Spherical ; in the form of an 

 orb. 



ORBICULATE. A depressed globe, whose 

 horizontal section is circular, and vertical 

 oval. 



ORBIT. The skin which surrounds the eye. 

 It is generally bare, but particularly in 

 the Parrot and the Heron. 



ORBITAL. Pertaining to the orbit of the 

 eye. 



ORDER. A subordinate division of the ani- 

 mal kingdom, bearing the same relation 

 to a class which this latter does to a king- 

 dom ; so that a class is made up of orders, 

 in the same manner as a kingdom is made 

 up of classes. 



ORDINATE. When spots, puncta, &c. are 

 placed in rows: thus we say ordinato- 

 punctate, ordinato-maculate, &c. 



ORGAN. A natural instrument of action or 

 operation, or by which some process is car- 

 ried on. Thus the arteries and veins of 

 animal bodies are orrjans of the circulation 

 of the blood ; the lungs are organs of res- 

 piration ; the nerves are organs of percep- 

 tion and sensation ; the ears are organs 

 of hearing ; the tongue is the oryan of 

 speech. 



ORGANIC BODIES. Such as possess organs, 

 on the action of which depend their growth 

 and perfection ; as in the case of animals 

 and plants. 



ORGANIC REMAINS. All animal and vege- 

 table substances which are dug out of the 

 earth in a fossilized state. 



ORGANIZATION. Structure ; suitable dispo- 

 sition of parts which are to act together in 

 a compound body. 



ORGANOLOGY. That branch of physiology 

 which specially treats of the different or- 



