FIGURE 4 in A new fossil subspecies of booby (Aves, Sulidae: Papasula) from Mauritius and Rodrigues, Mascarene Islands, with notes on P. abbotti from Assumption Island

FIGURE 4. Comparison of humeri of Papasula a. nelsoni ssp. nov. with Papasula a. abbotti, caudal surface, left side. A. NHMUK PVA9049 P. a. nelsoni (Plaine Corail, Rodrigues); B. UMZC 262.AA holotype P. a. nelsoni (Mare aux Songes, Mauritius); C. USNM 560863 P. a. abbotti u/s (Christmas Island); USNM 560862 P. a. abbotti immature u/s (Christmas Island). Abbreviations: td, tuberculum dorsale; tv, tuberculum ventrale; ch, caput humeri; ic, incisura capitis; mc, margo caudalis; cvf, crus ventrale fossa; cb, crista bicipitalis; fp, fossa pneumotricipitalis; sh, sulcus humerotricipitalis; ss, sulcus scapulotricipitalis; pf, processus flexorius. Scale bar = 20 mm.