OF THE IIYDROMEDUS^E. 367 



,/Eginopsis will probably be found to develop directly from the egg- without alternation; 

 a prophecy which was verified twenty-five } r ears later by Metschnikoff (51). 



The youngest larva which Muller figures, PI. xr, fig. 1, is a hydra essentially like 

 the one shown in our PI. 43, fig. 1. The position of the tentacles is different, but he 

 says in the text, that they are often carried as they are shown in our figure. 



In the autumn of the following year, 1852, three young naturalists, Gegenbaur, Kol- 

 liker and II. Muller, met at Messina to spend a few months in zoological research at 

 the seashore, and their fruitful harvest furnishes one with the earliest evidences of the 

 value of marine zoological stations. 



Kolliker, who studied the lower invertebrates, made many interesting observations on 

 the medusae, one of the most important being the discovery of young Cuninas in the 

 stomach of an old one, which he names Eurystoma rubiginosum {Cunina rubiginosa, 

 Haeck.). 



The oldest larvae are so similar to another Cunina which he found at the same place, 

 and named Stenogaster complanatus, that he decided that they were the young of this 

 species. He says nothing about budding from the stomach, and adopts the view, which 

 is undoubtedly correct, that they had gained access to the stomach from outside, al- 

 though he supposes that they had been swallowed by the Eurystoma as food. 



In 1854, Gegenbaur (24) found small bud-like bodies, each with four tentacles, at- 

 tached to the walls of the stomach of a Cunina, which he named Cunina prolifera, since 

 he supposed, from the fact that the larvae became adults of the same species, that they 

 are produced by budding. 



The observations which come next in historical order (1850) are by an American 

 naturalist, McCrady (48, 49), and they will always remain a monument to the accu- 

 racy of this sharp-sighted observer, for they give for the first time a pretty complete 

 history of the life of a Cunina, which is accurately illustrated and vividly described. 

 McCrady's papers are very different from the brief notices which have been referred to 

 above, and they are by far the most important which have ever appeared upon the 

 subject. They not only serve to throw a flood of light upon the significance of earlier 

 observations, but they also contain a record of facts which should have prevented the 

 confusion which later writers have introduced. Unfortunately the edition of his paper 

 was almost completely destroyed before it was distributed, and reference to it is now 

 nearly impossible, and although proper credit is now given to the author, a desire to 

 place the facts which it contains within the reach of all was as strong an inducement 

 to the preparation of this paper as my desire to publish my own additions to the subject. 

 I have illustrated some stages which he did not obtain, and my figures exhibit many points 

 which are not shown in his much smaller ones, but I have also copied a few of his orig- 

 inal figures, and I have embodied all the leading points of his paper, the chief results 

 of which are as follows: 



1. The young Cunina ortnuaria is a parasite inside the bell of a Hydromedusa, 

 Turritopsis. 



2. The larva is a hydra. 



3. It multiplies asexually by budding from an aboral stolon, and gives rise to other 

 larvae like itself. 



2 



