JURASSIC. 73 



Family EULITHOTID^l Haeckel. 



Genus EULITHOTA Haeckel. 



Eulithota fasciculata Haeckel. 



PI. XLV, tigs. .'.{, 4. 



Eulithota fasciculata Haeckel, 1869. Zeitschr. fur wiss. Zoologie, Vol. XIX, pp. 



549-553, 559, PI. XLII, figs. 1, 2. 

 Eulithota fasciculata Haeckel, 1880. System der Medusen, p. 617. 

 Eulithota fasciculata Ammon, 1886. Abhaudl. Math.-phys. Classe Konigl. bayeriscken 



Akad. Wiss., Vol. XV, p. 157. 



Dr. Haeckel' s descriptive remarks are essentially as follows: 1 



The impression of this medusa shows the animal lying on its oral side, and the 

 depth and distinctness of its outline bear witness to the considerable cartilaginous 

 consistency of the gelatinous mass. By a careful inspection it is shown that the 

 peripheral outline of the disk takes on almost the form of a regular octagon, while at 

 equal intervals lie eight pit-like depressions of an irregular form, directed radially. 

 These eight marginal pits have evidently been produced by some especially thick and 

 firm portion of the body rim, and probably by those well-known sense organs distin- 

 guished by the name of "rand-koerper" (marginal bodies), while the filaments stream- 

 ing out from them were probably formed by marginal tentacles. It is necessary to 

 believe that the latter belong to the hard and fast category of marginal tentacles 

 whose axis is supported by a central cartilaginous band, for tentacles of the other 

 class, which represent a thin-walled, hollow cylinder, could hardly, under the most 

 favorable circumstances, leave behind so sharp and distinct an impression. There is 

 in favor of this hypothesis the somewhat hard and stiff position of the tentacles of 

 our fossil, which is exactly as in the cartilage tentacles described by me. The 

 umbrella rim of our Eulithota appears to be supplied with tentacles only at the eight 

 prominent places where are the hollows of the " rand-koerper," or sense organs, and, 

 in fact, they form a tuft which was probably fastened immediately beneath the base 

 of the sense organ. Only four tentacles can be clearly and unquestionably made out 

 in each bunch, but probably their number was much more considerable. 



Arising from the octagonal periphery of the disk rim are 16 equal crescent- 

 shaped depressions, directed inward, and terminating outwardly in a smooth, sharply 

 defined convex curve. These can be nothing else than the 16 lobes of tlie deeply 

 indented umbrella rim. That they project convexly inward instead of outward is 

 easily explained by supposing that the disk of our medusa (as in many still living 

 forms) had its greatest diameter, not at the disk margin at the mouth of the umbrella 

 cavity, but some distance above the rim. Accordingly, the umbrella cavity must 

 have been wider above its orifice than at it. The indentation between any two mar- 

 ginal lobes is very deep. 



Centrally from the infolded lobes of the disk rim there follows, in our impression, 

 a rather strongly prominent ring which presents no especial structural features. It 



1 Zeitschr. fiir wiss. Zoologie, Vol. XIX, 1869, pp. 549-552. 



