166 INTERNAL CAST. 



INEQUILATERAL, (JEquus, equal; latus, a side.) A term ap- 

 plied to a bivalve shell when its extent on one side of the umbones 

 is greater than that on the other. When the sides are nearly 

 equal, the term sub-equilateral is used. 



INEQUIVALVE. (in ; cequus, equal ; valva, valve.) The two 

 principal valves differing from each other in diameter or con- 

 vexity. 



INFERIOR VALVE is that which is attached to sub-marine bodies. 

 Only applied to attached bivalves. 



INFEROBRANCHIATA. Bl. The fourth family of the second 

 section of Paracephalophora Monoica, Bl. containing no tes- 

 taceous mollusca. 



INFLATED. Swelled, as Bulla, fig. 250, 252. This term can 

 only be applied to rotund shells of a light, thin texture. In other 

 cases we should use the word Ventricose. 



INFLECTED. Turned inwards. This term is applied to the outer 

 lip of a spiral shell when it turns towards the body whorl. This 

 is the case in Cypreea, fig. 446. See Reflected. 



INFUNDIBULUM. Montf. (A funnel.) A genus formed of those 

 species of Calyptr^a, Lam. which, having a spiral septum, so 

 nearly resemble Trochus that some authors have placed them in 

 that genus. One species named Patella Trochiformis. Recent 

 from South America, fossil from the tertiary beds. Fig. 237, 238, 

 Calyptrsea (Infundibulum) Pileus. 



INNER LIP. That edge of the aperture of an univalve shell which 

 is near to the imaginary axis, as distinguished from the outer lip, 

 or that which is on the opposite side. 



INOCERAMUS. Sow. Fam. Malleacea, Lam. Margaritacea, Bl. 

 — Descr. Thick, inequivalve, sub-equilateral, triangular, deep, 

 with the umbones incurved ; hinge formed of a series of trans- 

 verse grooves. — Obs. The larger valves of these fossil shells re- 

 semble the larger valve of Gryphsea ; but the hinge is quite 

 distinct. The species described in Mineral Conchology are found 

 in the blue marl, at Folkstone, and in the chalk. I. Lamarckii, 

 (Catillus, Brong.) fig.167 . 



INTERNAL CAST. The mould of a fossil shell, composed of 



