Late Devonian Cavellina (Ostracoda) with Separate Receptacles for Eggs

Abstract

A NUMBER of ostracods, Cavellina lovatica Zaspelova, with separate receptacles for eggs in the females' brood pouches, have been found during boring operations in the Upper Devonian deposits of the Malaja Vishera district, in the Novgorod region. In the specimens found, at a depth of 76.10 m, there were eleven valves, mostly well preserved; they were large (up to 1,225 µm long) and thin-walled. The brood chamber is separated by a well-marked ridge, running from the ventral to the dorsal margin, and gradually narrowing. Inside the chamber, very shallow, round cavities, which we believe to be receptacles for eggs, can be seen (Fig. 1). Some of these are very distinct, although others have somewhat obscured outlines; the walls between them are thickened. The number of receptacles in the valves varies from individual to individual (Table 1). From this it may be seen that the total number of eggs could be as much as 24, although this might vary with individuals between 16 and 24, and this number can differ between the left and the right valves of the same female. The size of these cavities varies between 100 and 120 µm, and this figure might approximate to the diameter of the eggs.