Zur Morphologie des Vogelskelets, Moscou, Kouchnéreff, 1905, birds, anatomy, The illustration showcases a series of detailed anatomical drawings of various bird skulls from the subfamily Polyborinae. Each figure is meticulously labeled with corresponding numbers and scientific names, highlighting distinct features such as beak shapes, cranial structures, and overall morphology. The arrangement allows for easy comparison between different species, emphasizing the diversity within the group. The anatomical focus includes profiling, ventral, and dorsal views to provide a comprehensive understanding of their skeletal make-up relevant to ornithology and taxonomy.