JURASSIC. 91 
The second group of species described by Dr. Haeckel includes those 
whose systematic position can not be further determined. They are 
grouped under the genus Medusina. All are illustrated, with the exception 
of M. circularis. 
Genus MEDUSINA! Walcott. 
MEDUSINA DEPERDITA Beyrich (sp.). 
Pl. XLIV, fig. 1. 
Acalepha deperdita Beyrich, 1849. Zeitschr. Deutsch. geol. Gesell., Vol. I, pp. 437-439. 
Medusites deperditus Haeckel, 1865, Zeitschr. fiir wiss. Zoologie, Vol. XV, pp. 506-508, 
17d 0.0.0.4 Big ives ae 
Trachynemites deperditus Haeckel, 1869. Zeitschr. fiir wiss. Zoologie, Vol. XIX, p. 560. 
Medusites deperditus Leuckart, 1870, Jahresber. ueber Acalephie: Archiv. fiir Natur- 
gesch., Wiegmann, Vol. II, p. 280. 
Acalepha deperdita Brandt, 1871. Mélanges biolog. tirés du Bull. de l’Aead. St. 
Pétersbourg, Vol. VIII, pp. 71-180. 
Medusites deperditus Haeckel, 1880. System der Medusen, p. 647. 
Medusites deperditus Ammon, 1886, Abhandl. Math.-phys. Classe Konig]. bayerischen 
Akad. Wiss., Vol. XV, p. 158. 
The original description by Beyrich is brief, and calls attention to the 
occurrence of the fossil in the lithographic slates. It was followed, in 1869, 
by Dr. Haeckel’s historical notes and elaborate description of the mode of 
occurrence of the fossil medusze of the Jurassic. Dr. Haeckel again speaks 
of the species as the first described, and as the only one of which he had 
more than one similar impression. From the peculiar stiffness and regu- 
larity of form in all the impressions, his conviction was strengthened that 
this medusa belongs to the family Trachynemide. 
All that was known of this species by Dr. Haeckel is shown in the 
figure (Pl. XLIV, fig. 1) and in the accompanying description. Leuckart 
examined the specimens of M. deperditus, and concluded that the eight ridges, 
interpreted by Haeckel as radial canals, are arranged in pairs, and hence 
their significance is doubtful. 
Dr. Brandt studied a plaster cast of the Carlsruhe specimen (fig. 23, 
p- 92) and found it to differ from the figure given by Haeckel. He con- 
siders that there is no doubt of the specific identity with Acalepha deperdita. 
He regards the rosette (which Haeckel appears to have overlooked) as the 
1 See p. 49. 
