58 
GUIDE TO THE CORAL GALLERY. 
Case 3, jecting from the stomach walls are four groups of gastral filaments 
Upright part. ][ oa( j e( j with thread-cells. The purple reproductive masses project 
from the floor of the stomach cavity ; at the base of the manubrium 
outside are four pockets, which bring the water very near to these 
masses. Aurelia has no velum in the adult state. The fertilised 
egg develops into a hollow oval ciliated embryo, which settles down 
and becomes a small polyp with mouth and stomach and sixteen 
tentacles ; this phase was formerly supposed to be a distinct 
individual, which was named Hydra tuba , or the Trumpet Polypus. 
A very fine example sent by the Plymouth Biological Station is 
exhibited in Case 3 (Fig. 19a), numerous specimens of the little 
Fig. 21. 
Tentaculocyst and marginal lappets of Aurelia aurita. In the left-hand figure 
— ml, marginal lappets; t, tentaculocyst ; a, superior olfactory pit; mi, mar- 
ginal tentacles of the disc, magnified about 50 diameters. In the right- 
hand figure — a, superior olfactory pit ; b, inferior olfactory pit ; h. hood or 
bridge joining the marginal lappets ; t, tentaculocyst ; con, auditory con- 
cretion ; oc, ocellus. (After Eimer, from Encyc. Britannica.) 
polyp being attached to a shell ; this fixed phase of Aurelia is now 
called the “ Scyphistoma ” stage, on account of the shallow cup- 
like oral region, contrasting in this respect with the elongated narrow 
conical oral region of Hydra and Hydroid polyps. In course of 
time the little Scyphistoma undergoes “ transverse fission,” and 
resembles a pile of saucers with crenulated rims (Fig. 19b). 
Presently the saucers detach themselves (specimens, Case 3) and 
swim away ; they are now known as Ephyra Medusae, or the 
Ephyra stage (Fig. 19c ; specimens, Case 3) ; the last stage in this 
wonderful transformation consists in the filling in of the spaces 
between the eight bifid arms of the Ephyra aud the development of 
