GLOSSARY OF TECHNICAL TERMS. 350 
Mullerian duct. A longitudinal division of the archinephric duct opening into 
the ccelome near the vanishing pronephros. 
Musculo-cutaneous veins. . Veins carrying the blood from the skin and muscles 
on the side and back, and part of the head, to the brachial veins. 
Nape. Neck above, next to the occiput. 
Nares. Nostrils. 
Nasal bone. Pair of bones of the nose in front of the frontals. 
Nasal plates. Scaly plate, or plates, in which the nostril is placed, or placed 
between, in lizards and snakes. 
Neural arch.’ Bony arch formed from upper part of the centrum. 
Neural plates. Flattened neural spines forming median bony framework of 
the carapace in turtles. 
Neural spine. Uppermost spine of a vertebra. 
Nictitating membrane, Third.or inner eyelid. 
Notocord. A cellular cord, preceding the vertebral column, in the embryo. 
Nuchal shield. The most anterior of the median marginal shields on the cara- 
pace of turtles. 
Obliquus externus. A layer of oblique muscular fibres extending from the 
vertebral column to the recti. 
Occipital. Relating to the occiput. 
Occipital plates. A pair of narrow plates behind the parietals in lizards and 
serpents. 
Occiput. Back of head above. 
Ocellate. Eye-like, usually roundish. with a lighter or darker border. 
Oculomotor nerves. ‘Third pair of cranial nerves, supplying muscles of the 
eyes. 
Oid. Like, as a suffix, such as. 
Olfactory capsules. Front region of skull on each side of the brain-case. 
Olfactory nerves. First pair of cranial nerves, supplying the organ of smell. 
Omosternum. Plate of cartilage at end of episternum. 
Opisthocelian. Concave behind only, usually referring to ball-and-socket- 
jointed vertebre. 
Opisthotic. Bone of skull to which lower limb of post-temporal usually 
articulates. 
Optic lobes. Paired oval swellings from the dorsal wall of the mid-brain. 
Optic nerves. Second pair of cranial nerves, supplying the organ of sight. 
Optic thalmi. ‘The thickened sides forming paired masses to the diencephalon. 
Optocele. Ventricle of the optic lobe. 
Ora serrata. A very delicate membrane over the ciliary processes and the 
posterior face of the iris. 
Orbicular. Nearly circular. 
Orbit. Eye-socket. ; 
Orbitosphenoids. Paired bones at presphenoid, forming side walls to the inter- 
orbital regions. 
_Osteology. Study of bones. 
Otic process. A proximal fork of the suspensorium fusing with the auditory 
region of the cranium: 
Oviparous. Producing eggs developed after exclusion from the body. 
