374 



Interapertiival — between the apertures. 



InterhracluRls — the plates in the calyx of a Crinoid, lying be- 

 tween the brachials. 



In tercaln tion — irregular interjjosition . 



Intercellahir — between the cells or meshes. 



Interdistichals — the plates in the calyx of a Crinoid, lying 

 between the distichals. 



Interradmis — the plates in the cah'x of a Crinoid, lying 

 between the radials. 



Interstitial — pertaining to an intervening space; between 

 lines, plications, etc. 



Intrathecal — within thetheca; endo-thecal. 



Introverted — turned apex to apex; applied to the spirals of 

 Brachiopods. 



Keel — a strong central carina or ridge (TcPniopora). 



Lacrvniifonn — tear-forni ; drop -shaped — pear-shaped in 

 form, but Avithout the lateral contractions. 



Lawellose — made up of lamellae 



Lateral gemmation — a budding from the sides, as in some 

 corals. 



Ligament — the external structure for opening the valves in 

 the Pelecypoda. 



Limb — the lateral area or marginal band of the cephalon of 

 Trilobites on either side of the glabella, corresponding to 

 a pleu]"on of the thoracic region. 



Linguiform — tongue-shaped. 



Linguloid — tongue-shaped; like Lingula. 



Lip — the margins of the aperture of univalve shells. 



Listrium — the depressed area surrounding the pedicle open- 

 ing in the pedicle valve of Orbiculoideaand other discinoid 

 Brachiopods. 



Lobes — the backward bending portions of the suture of 

 Cephalopod shells. 



Lophophore — the ciliated, or tentaculated oval disk of Bry- 

 ozoa ; the oval disk and brachia of Brachiopods. 



