CASSIOPEA XAMACHANA. 209 



Diatoms and other algae, exclusive of the above-mentioned zoanthelae, were found 

 in four cases out of the twenty-two. Almost always the first impression on opening a 

 stomach was that it was empty; and it was only by careful examination that the contents 

 of the stomach could be discovered. In two cases, however, a considerable amount 

 of material was found in the stomach. In one of these the stomach contained, besides 

 the usual eggs, zoanthelae, debris, etc., the remains of many copepods, some nematods, 

 a zoea, and some diatoms. In the other one there was found a compact greenish mass, 

 about one centimeter in diameter, composed of grjinular debris and diatoms of various 

 species, together with some desmids, Oscillaria, foraminifera, infusoria, Vorticella, and 

 some fine filaments with spirally arranged contents. 



This species exhibits the power of regeneration of lost parts to a marked extent. 

 Specimens were frequently met with in which branches of the oral arms, or even portions 

 of the margin of the umbrella, had evidently been formed recently to replace parts that 

 had been destroyed. Moreover, branches of the oral arms that had been cut off were 

 observed to reg-enerate oscula and vesicles at the central end. 



Ontogeny. 



Historical Review. — Numerous studies upon the reproduction of various animals 

 by budding have shown that the formation of organs in the bud may take an entirely 

 different course from the development of homologous oi'gans in the sexually produced 

 embryo. As the observations to be described in the sequel were made entirely upon 

 larvae that were observed, or supposed, to be asexually produced, they cannot settle 

 any of the disputed points in regai'd to the development of sexually produced larvae. 

 Nevertheless it will be of interest to compare the sexual with the asexual mode of 

 ontogeny, especially as the development of a scyphistoma from a bud has never before 

 been fully described. 



The development of scyphomedusae from the egg has been studied in comparatively 

 few forms. Several species of Aurelia have been studied by Sars, Haeckel, Schneider, 

 Clans, Goette, Frank Smith, and Hyde. Two species of Cyanea have been studied by 

 McMurrich and Hyde. A species of Chrysaora has been studied by Claus; and 

 Kowalewsky, MetschnikofF, Krohn, and Goette have traced the very interesting abbrevi- 

 ated development of Pelagia noctiluca. The nearest ally of our species that has been 

 studied with any degree of completeness is the Mediterranean rhyzostome Cotylorhiza 

 tuherculata, which has been the subject of investigation by Claus and Goette. 



From the description of the process of budding given in the next section, it will be 



