A dissertation by Swedish physician F. Josef A. Rossi (1774-1854) describing a case of sirenomelia, or mermaid syndrome: a rare condition in which a fetus's legs are fused together, creating the appearance of a mermaid's tail.
Rossi is probably best remembered as the personal physician of King Charles XIII and crown prince Charles August.
A case of sirenomelia, or mermaid syndrome, with a folding plate
Franz Joseph Anton Rossi.
Dissertatio inauguralis medica sistens foetus monstrosi Holmiae nati descriptionem et delineationem.
Jena, Prager, 1800.