THE 



VOYAGE OF H.M.S. CHALLENGED 



ZOOLOGY. 



REPORT on the Deep-sea Medusa dredged by H.M.S. Challenger during the 

 years 1873-1876. By Prof. Ernst PLeckel. 



PREFACE. 



The Deep-sea Medus/E form one of the smallest and least important groups of the 

 rich and remarkable deep-sea fauna for whose discovery we are indebted to the voyage of 

 H.M.S. Challenger; the number of the species described does not exceed eighteen, of 

 which half are Craspedotas and half Acraspedse. The majority of these eighteen species, 

 however, which represent an equal number of genera, are of great morphological interest, 

 and they, moreover, claim special attention as the first deep-sea inhabitants of this class 

 of animals with which we have become acquainted. I am therefore particularly in- 

 debted to Sir Wyville Thomson for most liberally handing over to me for examination 

 the whole of the Medusas collected by the expedition. To the first large collection of 

 deep-sea Medusae, sent to me in 1877, I was able to add a few more, which I found 

 incidentally in examining the Radiolaria of the expedition, and in going more minutely 

 over the general collection, during a visit to Edinburgh in 1879. I have especially to 

 thank Mr. John Murray, principal assistant on the civilian staff of the Challenger, for 

 kindly aiding me in this work in every way in his power. 



All the eighteen species of deep-sea Medusae described in this Memoir have already 

 received a brief diagnosis in my System der Medusen published in 1879. Besides 

 these, I had already described two other species, the iEginid, sEginorhodus rosarius 

 (System, p. 345, No. 379), and the Cyaneid, Melusina formosa (System, p. 535, No. 500). 



2. (ZOOL. CHALL. EXP. PART XII. 1881.) M a 



