90 



FOSSIL MEDUS.E. 



as interpreted by himself, the new name Pelagiopsis leuckarti He states 

 that instead of 48 marginal lobes and 8 feeding- arms, which Haeckel 

 described, he found only 10 lobes and 5 arms. The view, therefore, that 

 the fossil is a rhizostomide is erroneous, since it possesses a wide mouth 

 surrounded by a number of channel-shaped arms. Its most striking- pecu- 

 liarity consists in the pentameral symmetry of the organism, there being 5 

 mouth arms and genital cavities and 10 marginal lobes. In its general 



structure it may be compared with Pelagio, 

 although it has no traces of marginal tentacles. 

 Dr. Brandt is in doubt, however, about the true 

 relations of this fossil, as he can not vouch for 

 the existence of the 5 arms and genital cavities 

 and the 15 marginal lobes. 



Dr. Ammon agrees with Dr. Brandt as to the 

 facts observed, but not at all as to his conclusions, 

 and he even considered that L. trigonobrachius is 

 a laterally crushed specimen of the same species 

 shown by the oral impressions in R. admirandus 

 and B. lithographicm. 



The interpretations of this species as made 



by Haeckel and Brandt, respectively, are shown 



in the two accompanying diagrammatic figures 



(figs. 21, 22). 



The illustrations of the specimens of this species by Haeckel and Brandt 



are so obscure that I think their reproduction here would not be of sufficient 



service to the student to warrant the attempt. 



Fig. 22. — Contour drawing of the same 

 fossil (fig. 21) according to Haeckel's resto- 

 ration, reduced, and, owing to reduction, 

 reversed (right and left interchanged). 



I-YIII. Mouth arms. 



Leptobrachites gigantea Haeckel. 



Palcegina gigantea Haeckel, 1809. Zeitscbr. fiir wiss. Zoologie, Vol. XIX, pp. 540-544, 



559, PI. XL. 

 Leptobrachites gigantea Haeckel, 18S0. System der Medusen, p. 647. 

 Leptobrachites gigantea Atamoii, 188G. Abbaudl. Matb.-pbys. Classe Konigl. bayer- 



iscben Akad. Wiss., Vol. XV, p. 158. 



Dr. Ammon states that L. gigantea should, without doubt, be struck from 

 the list of the medusa?, as it represents the circumference of the head and 

 the arms of a cephalopod. The shell of the animal is also found on the 

 same slab of limestone with the impression of the head and arms. 



