Paddy field frogs of both sexes showed excellent positive correlation between body weight and snout to vent (S-V) length, body weight and bone weight as well as body weight and gonad weight, suggesting the utility of these parameters as indirect markers of chronological age and indicating continuous structural growth. The relative weight of bones of both sexes increased up to maturation and then gradually decreased with body weight, showing slower rate of growth of these organs with advancing age. The observation of gonad indicates that this paddy frogs become sexually mature when they attain a body weight of about 9-10 grams in both sexes. However, reliability of such morphometric data needed report from a more accurate method of bone histology based on the techniques of `skeletochronology'.

`Skeletochronology' is a method which uses various hard tissues, histological characteristics and growth marks in bones for the purpose of individual age determination [1]. It is often used as part of amphibian and reptile demographic investigations. Although unstained flat bones have been employed for this purpose [2], cross sections of the diaphyseal shaft of long bones stained with haematoxylin are frequently used in recent studies of reptiles [3], urodeles [4] and anurans [5-10].

Most of the haematoxylinophilic Resting Lines (RL) present in skeletal tissues of many vertebrates are the result of arrested bone growth or Lines of Arrested Growth (LAG) during winter and summer periods [11-12]. However, resorption of periosteal bone around the medullary cavity in long bones has been shown to reduce the number of RL in some anurans [12-14]. The present study reports use of LAG counts to assess the individual age and growth rate of paddy field frogs, Rana limnocharis.

Paddy field frogs, Rana limnocharis, (Ranidae) of both sexes of various sizes used in the present study were collected from Baliapal of Balasore district, Orissa (21° 41' 15" N and 87° 20' 10" E). Morphometric parameters, like total body weight, snout to vent (S-V) length, bone (humerus and femur) weight and gonad weight were measured. The method followed for bone histology is the same as those used earlier [10, 15-16].

Science and Technology Journal, Skeletochronology, Paddy Field Frog, Reptile Demographic Investigations, Haematoxylinophilic Resting Lines, Morphometric Parameters, Rana Limnocharis, Subtropical Species, Post-morphotic Growth Rate, Ehrlich Haematoxylin, Lines of Arrested Growth, Suntron Model.