Introduction

Most female oviparous reptiles ovulate and shell a few to several eggs at the same time to produce a clutch that is normally laid as a unit. This differs significantly from the normal procedure in birds, in which individual eggs in a clutch are each ovulated, shelled, and oviposited separately (usually on a 24-hour cycle in the fowl (Gallus gallus); Gilbert, 1971). Egg size and number within a clutch are clearly important aspects of an organism's life history ‘strategy’ (Smith & Frerwell, 1974; Stearns, 1976). Egg size, shape and number also may be related to the anatomy of the female (e.g. ovarian follicle size, oviductal length and diameter, abdominal volume, and size of the pelvic canal), as well as to the physiological ecology of the clutch in the nest. For reptiles, evidence is available that suggests that life history strategies (Moll, 1979; Ferguson, Brown & DeMarco, 1982; Dunham, Miles & Reznick, 1988; Seigel & Ford, 1987; Ford & Seigel, 1989), pelvic canal size (Congdon & Gibbons, 1987; Long & Rose, 1989), and nest physiology (Packard & Packard, 1988) do place important constraints on egg size, shape, and number. However, the influence of the anatomy and physiology of the female reproductive tract on egg parameters has not been explored in reptiles.

Although numerous studies report clutch sizes, lengths and widths of eggs in reptiles, and some even report data on mass, volume, or other aspects of egg-shape, no synthesis of egg size and shape has been attempted for reptiles at the level done for birds, which includes aspects of size, volume, density, surface area, and shape (Preston, 1953, 1969, 1974; Paganelli, Olszowka & Ar, 1974; Tatum, 1975; Rahn, Paganelli & Ar, 1975; Hoyt, 1976; Smart, Chapter 8).