44 ifl'lDE TO THE EOSSII, INVEHTEBKATE ANIMALS. 
Q-allfil’y X. rosciiililo in tliG siiii])l6 iiiuutli Jiiul iibsyiicc of inc.soutGries j 
otliers place them with the Aiitliozoa, wliich they reseml)]e 
in tlie origin of tlie reproductive cells. Other featines, 
however, distinguish them i'rom both these Cla.sses. 
('L.\ss SCYPHOZOA. 
Many Coelentera being .soft-bodied animals can leave no 
fossil traces except impre.ssions that they may have formed 
Fig. 18. — A fossil jelly-fish, lihizostomitcs lithographicus, oue of the Scypho- 
medusae, from the Kiinmoridgiau of Solenhofen. o, imprint ou the 
exposed surface of the Lithographic Stone, about j natural size. (From 
E. Hay Lankester’s “ Extinct Animals.” After Walcott.) 6, diagram 
interpreting the marks seen in a. (After Hrandt.) c, diagram to show 
how the imprint is formed by the jelly-fish settling down on the mud ; 
a vertical cut has been made through the mud and through the middle 
of the jelly-fish. (After Walcott.) 
on a sandy shore ; thesis of course can only be left by free- 
swimming jelly-lishes or medusae, not by fixed forms. Such 
imjiressions are actually known in various rocks from the 
