168 ZOOLOGY. 



Nematoidea (Gr. nema, thread; eidos, form) A group of Scokcida, 



including the "thread worms" and the "round worms." 

 V Neural (Gr. neuron, a nerve) Belonging to the nervous system. 



Nucleated Possessing a nucleus or central solid particle. 

 Nucleolus A minute particle attached to the " nucleus," or sup- 

 posed ovary of the Infusoria. 



Occipital Belonging to the occiput, or that part of the skull which 



forms the back portion of the head. 

 Ocelli (Lat. diminutive of ocuhis, eye) The simple eyes of 



spiders, crustaceans, molluscs, and some insects. 

 Octopoda (Gr. octo, eight ; pous, foot) A group of cuttle-fishes, 



possessing eight arms. 

 Odontophore (Gr. odous, tooth; phero, I fear) The lingual ribbon, 



or tooth-bearer, of the higher Mollusca. 

 (Esophagus (Gr. olsos, a reed; phago, I eat) The tube leading 



from the mouth to the stomach.. 

 tOperculum (Lat. a lid) The bony flap which covers the gills of 



fishes ; the horny disc which closes the shells of the Gastero- 

 poda. 

 M)rnithodelphia (Gr. ornis, a bird; delphus, womb) The lowest 



division of the Mammalia, including the Monotremata. 

 Oscula (Lat. diminutive of os t mouth) The large or exhalant 



apertures of sponges. 

 Otoliths (Gr. 'ous, ear; lithos, stone) Concretions found in the 



auditory sacs of fishes, Crustacea, and Mollusca. 

 tXJvoviviparous (Lat. ovum, egg; vivo, I live; pario, I bring forth) 



A term applied to those animals which retain the eggs 



within their bodies until they are hatched. 



Pallium (Lat. a cloak)The "mantle" of the Mollusca; "pallial 

 line," the impression left in the shell by the muscular margin 

 of the mantle. 



Palpi (Lat. palpo, I touch) Organs of touch connected with the 

 appendages of the mouth in the Arthropoda. 



Parietal (Lat. paries, a wall) Belonging to the walls of the body. 



Parieto-splanchnic (Lat. paries; Gr. splanclma, the internal organs) 

 A ganglion in the higher Mollusca, which sends nerve- 

 fibres to the mantle, gills, and internal organs. 



Pectoral (Lat. pectus, the chest) Belonging to the chest. 



Pedal (Lat. pes, foot) Belonging to the foot, in Mollusca. 



Pedicellarise (Lat. pedicdlus, a louse) Curious appendages at- 

 tached to the sea-urchins. 



Peduncle (Lat. pedunculus, a stalk) The muscular stalk by which 

 the Brachiopoda are attached; the stem by which the bar- 

 nacle connects itself with wood or other objects. 



