THE MEDUSA. 23 



inner siu-face of the bell, directly opened. Midway 

 between these four canals, under favorable circumstances 

 and with a good light might be observed some fine lines, 

 which I looked upon as smaller canals of the same kind. 



During the first few days in which the animals were 

 under my observation, I perceived no other internal 

 organs ; but at a later period, I observed at the bottom 

 of the cavity of the body, a four-sided projection (figs. 36 

 and 38,) in which there was a hoUow, usually square. 



Frequently, when the bell and the annular membrane 

 around its orifice were extended, I have seen this quad- 

 rangular organ which is toothed at the extremity, become 

 elongated and project as far as the orifice, being placed in 

 the middle of the cavity like the clapper of a bell. At 

 other times, when the body has been much depressed, so 

 as not to be more than a quarter of its usual height, and 

 has presented at its circumference, as it were, four lobes, 

 this organ has projected more than half its length from 

 the mouth of the bell (fig. 37;) on which account, I could 

 no longer in any way doubt, that it was really an oral 

 opening and oesophagus, such as we find in the Medusce, 

 as for instance in the maternal animal, the Medusa aurita. 

 But besides this point of resemblance we actually find also 

 a vascular system, consisting of annular canals, connected 

 by radiating vessels, and resembling that system of organs 

 in the full-grown animal, together with a number of ten- 

 tacula, which are produced gradually and in a definite 

 order, hke the tentacula of the self-developing Medusce, in 

 a word we recognize in this apparently polypoid animal, 

 an actual Medusa, hut tühich is fixed. 



These polypiform Medusae thus enjoy a mode of de- 

 velopment peculiar to themselves before the period at 

 which Medusa-larva are formed in their abdomen (if such 

 a term may be here applied,) and there is no observation 

 to show that they undergo any further development after 

 the formation and detachment of the larvce ; on the con- 

 trary, it has been observed that when the larvae approach 

 the complete term of their growth, the trunk or stem is 

 found without such polypoid animal upon it. 



