JURASSIC. 67 



description of two fossil medusae, one of which was Beyrich's Acalepha 

 deperdita, which afterwards proved to be specifically identical with the 

 specimen mentioned by Agassiz. He also described Medusites antiquus, 

 and referred Beyrich's species to Medusites, placing, however, the two 

 species under the genera Craspedonites (C. deperditus) and Acraspedites (A. 

 antiquus) } 



Dr. Haeckel, in 1866, described two additional species from the Solen- 

 hofen slates, referring them to the family Rhizostomae. The two species 

 Rhizosto mites admirandus and R. lithographicus are illustrated by two very 

 good plates. 2 This was followed, in 1870, by the description of several new 

 genera and species. These include : Palcegina gigantea, Leptobrachites trig- 

 onobrachius, Eulithota fasciculata, Medusites quadratus, M. bicinctus, M. staur- 

 ophorus, M. circularis, and M. porpitinus. He also described RMzostomites 

 admirandus H, R. lithographicus H., Acraspedites antiquus H, and Trachyne- 

 mites deperditus H. 3 In 1 87 1 Dr. Brandt published a memoir of RMzostomites 

 admirandus, R. lithographicus, and Leptobrachites trigonobrachius, illustrating 

 the species and giving restorations of the two rhizostomes. 4 In the same 

 year he published an historical review of fossil medusae literature and a 

 discussion of Acalepha deperdita Beyrich. 5 



Dr. Haeckel returned to the study of the fossil medusas again in 1874, 

 and described two new species of Discomedusae under the names Hexarhi- 

 sites insignis H. and Sem&ostomites zitteli H. 6 



In 1886 Dr. Ludwig von Ammon published a memoir 7 in which he 

 reviewed the work of his predecessors on the fossil medusae and gave the 

 results of his own studies on some new material from the Jurassic rocks of 

 Bavaria. Hexarhizites insignis H. is considered to be a synonym of RMzos- 

 tomites lithographicus, and Leptobrachites trigonobrachius as possibly a laterally 

 crushed form of the same species. Leptobrachites giganteus H. is said to 



1 Ueber fossile Medusen : Zeitschr. fur wiss. Zoologie, Vol. XV, 1865, pp. 504-514, PL XXXIX. 

 2 Neues Jahrbnch fiir Min., Geol. und Pal., 1866, pp. 257-292, Pis. V, VI. 



3 Ueber die foBsilen Medusen der Jura-Zeit: Zeitschr. fiir wiss. Zoologie, Vol. XIX, 1869, pp. 

 538-562, Pis. XL-XLII. 



4 Ueber fossile Medusen : Mem. Acad. imp. sci. St. Petersbourg, 7th series, Vol. XVI, No. 11, 

 1871, pp. 1-28, Pis. I, II. 



B Nachtragliche Bemerkungen neber fossile Medusen : Melanges biolog. tires du Bull, de l'Acad. 

 St. Pe'tersbourg, Vol. VIII, 1871, pp. 168-180. 



6 Ueber eine sechszahlige fossile Rhizostomee, etc. : Jenaische Zeitschr., Vol. VIII, 1874, pp. 

 308-330, Pis. X, XI. 



7 Ueberneue Exemplare von jurassiscben Medusen: Abhandl. Math.-phys. Classe Konigl. baye- 

 rischen Akad. Wiss., Vol. XV, 1886, pp. 105-168, Pis. I-V. 



