Abstract <p>The morphometric characteristics of the chromosomes, both meiotic and mitotic, in the eggs and embryos of the Black Sea scallop, <i>Flexopecten glaber</i> <i>ponticus</i> (Bucquoy, Dautzenberg &amp; Dollfus, 1889), were studied using the aceto-orcein staining method. Both metaphase I and metaphase II of meiosis were established to show 14 bivalents in each. The scallop karyotype consists of 28 chromosomes: two pairs of large subtelocentric (pairs 1–2), three pairs of submetacentric (pairs 3–5), and nine pairs of metacentric chromosomes (pairs 6–14). The average length of homologous chromosomes varied from 1.87 to 5.30 µm. The total length of the haploid set of chromosomes was 44.90 µm. The results obtained allow for chromosome pairs of the Black Sea scallop to be identified, contributing to the construction of an ideogram suitable for a comparison with the karyotype of the Mediterranean scallop, <i>F. glaber</i>.</p>