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 31. circularis. 



Genus MEDUSINA 1 Walcott. 



Medusina deperdita Beyrich (sp.). 



PI. XLIV, fig. 1. 



Acalepha deperdita Beyricb, 1849. Zeitschr. Deutscb. geol. Gesell., Vol. I, pp. 437-439. 

 Medusites deperditus Haeckel, 1865. Zeitschr. fur wiss. Zoologie, Vol. XV, pp. 50(J-50S, 



PI. XXXIX, fig. 1. 

 Trachynemites deperditus Haeckel, 18G9. Zeitsclir. fur wiss. Zoologie, Vol. XIX, p. 500. 

 Medusites deperditus Leuckart, 1870. Jahresber. ueber Acalepb;e : Arcbiv. fur Natur- 



gescb., Wiegniann, Vol. II, p. 280. 

 Acalepha deperdita Brandt, 1871. Melauges biolog. tires du Bull, de l'Acad. St. 



Petersbourg, Vol. VIII, pp. 71-180. 

 Medusites deperditus Haeckel, 1880. System der Meduseu, p. 647. 

 Medusites deperditus Amnion, 1886. Abbaudl. Matb.-pbys. Classe Konigl. bayeriscben 



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, iu I860, 

 by Dr. Haeckel's historical notes and elaborate description of the mode of 

 occurrence of the fossil medusae 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 Trachynemidse. 



All that was known of this species by Dr. Haeckel is shown in the 

 figure (PI. 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. '.(2) 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 Seep. 49. 



