JELLY-FISHES. 



93 



medusa of pinkish color and eight marginal sense bodies, alternating with as many ten- 

 tacles oil the bell margin. From the under side of the bell the oral appendages hang- 

 far outside of the bell cavity, resembling in many particulars the oral tentacles of the 

 genus Aurelia. Pdagia is not a large medusa, and is very remarkable in its develoj)- 

 meiit, as will be explained more at length later in our account of this part of the subject. 

 Dactylometra is closely allied to Pelar/ia, but has a larger number of tentacles around 

 the bell rim. The sense body of both these genera ditfers in important particulars 

 from those of the families already described. 



Flc. K5. — Dactijlometra quiiiqu 



Fig. 80. — l\ta(jia cijanella. 



The aberrant families of the Diseophora are among the most wonderful of tliis 

 group. A mention of a few of these may not be without interest. One of the most 

 abundant medusre at times in the neighborhood of the Florida Keys is a Discoiihore, 

 called by naturalists Linerges, and known to fishermen there as the " thimble-fish," " mut- 

 ton-fish thimble," and by similar designations. Under proper conditions the number of 

 individuals of this strange genus is very great, and they may be often seen extending 

 in the water in long lines, where they are thrown by the tide-eddies and ocean currents. 

 The popular name of thimble-fish designates exactly the form which these medusa' 

 assume. The bell is not unlike in size and shape a common thimble, differing consid- 

 erably in this respect from that of the other jelly-fi.shes of the Discophorous type. The 

 bell has a brownish color on its lower floor, and its walls have a bluish tinge. Around 

 the bell margin there are sixteen marginal lappets or rounded lobes, between which, 

 alternating with each other, there are eight rudimentary tentacles, and the same nmn- 

 ber of marginal sense bodies. Each sense body is covered bj a gelatinous extension of 



