368 W. K. BROOKS ON THE LIFE-HISTORY 



4. Each larva finally becomes metamorphosed into a medusa, and there is no alter- 

 nation of generation s. 



McCrady's papers were published in 1S56 and 1857, and at about the same time (185G) 

 Leuckart (47) figured and described a Cunina larva under the name Pyxidium truncatum 

 (PI. 11, fig. 7), but he gives no account of its history. 



In 1860, Keferstein and Elders (72) repeated Gegenbaur's observations upon a Cu- 

 nina which they call JEgineta gemmifera, but which is probably the same as JEgineta 

 (Cunina) prolifera, Gegenb. They were ignorant of McCrady's work, and believed 

 with Gegenbaur that the larvae are formed as buds from the Avail of the stomach. 



In 1861, Krohn published the observation above referred to, made in 1813, to the 

 effect that peculiar bud-like bodies are sometimes found on the gastrostyle of Geryonids, 

 and the same volume of the Archiv f. Naturgeschichte contained a paper by Fritz Midler 

 (56), in which he says that, in 1860, he found on the gastrostyle of a Brazilian Geryonid, 

 Liriope catherinensis, a group of medusa-buds, each of which became metamorphosed 

 into a young Cunina closely resembling an adult Brazilian Cunina which he names 

 Cunina Kbllikeri. In the same paper he says that in 1859 he found in the stomachs' 

 of male specimens of the Cunina, young ciliated larvae which became young Cuninas, 

 differing from C. Kollikeri, in the number of tentacles. He holds that the larvae found 

 in the stomach of the adult Cunina are asexual buds from the Avails of the stomach, 

 while he believes that those found in the stomach of the Geryonid have been swallowed 

 as food. 



In 1865, Noschin published a paper (57), in which he states that he has found on the 

 gastrostyle of Geryonia (Carmarina) hastata, bud-like larvae which became medusas 

 which he identifies as young specimens of Keferstein and Ehlers' Cunina discoidalis. 

 He regards this as a case of alternation of generations, and advances the astonishing- 

 hypothesis that the Geryonid, a Trachomedusa, and Cunina, a Narcomedusa, belong to 

 the same cycle, and that the buds which become Cuninas are produced by the Carmarina. 



In the same year Hacckel published a brief preliminary abstract and two fully illus- 

 trated papers (29, 30), in which he describes the same facts, and adA'ances, independently 

 the same astonishing hypothesis, but the mistake is the more remarkable in this case 

 since Haeckel had himself traced the metamorphosis of Carmarina from a very young 

 and small larval medusa, which, as he correctly conjectures, is an egg-embryo (30 d). 

 If Ave believe that the Cunina buds are also produced by the Carmarina, Ave are com- 

 pelled to believe that this medusa has tAvo methods of reproduction, producing Geryo- 

 nids like itself from eggs, and producing Cuninas from internal buds. Haeckel boldly 

 accepts this hypothesis (30 a, p. 184), and says on p. 293, "I do not 'doubt that what 

 I have here described as a remarkable exception Avill in time be found to be a widely dis- 

 tributed occurrence, at least among the lower medusae, especially the JEginidae. Allo- 

 triogenesis or alloeogenesis, as this form of reproduction may be called, is very essentially 

 different from all forms of alternation of generations." Haeckel's papers are beautifully 

 illustrated, and his figures show that although the proboscis of his larva is shorter than 

 that of Cunina octonaria, and the number of buds which are produced very much 

 greater, there is, in all other respects the closest resemblance to the American larva as 

 described by McCrady, with whose work Haeckel was not acquainted. 



