CRADACTIS VARIABILIS: AN APPARENTLY NEW TORTUGAN 



ACTINIAN. 



By Charles W. Hargitt. 



Dr. J. F. McClendon, during his stay at the Tortugas Laboratory 

 of the Carnegie Institution of Washington, collected a few aetinians for 

 some experiments on behavior, which he afterward preserved and later 

 turned over to the writer for identification. This I was very glad to 

 undertake, but found the task somewhat more difficult than had been 

 anticipated, owing chiefly to lack of some of the older literature pertain- 

 ing to the region and to the fact that the specimens were in a rather poor 

 state of preservation. Fortunately, however, Dr. McClendon had made 

 photographs of the specimens in the living conditions of his aquaria, a 

 few of which appear in the accompanying plate. Details of internal 

 morphology I shall defer till a later time, hoping that additional material 

 may enable me to make it more accurate and adequate. 



There seems to be no doubt as to the place of the species in the 

 family Phyllactidae ; concerning the generic relations I find myself more 

 or less uncertain. There are phases of likeness with several genera, e.g., 

 Lebrunia Duch. and Mich., Oulactis M. Edw., and Cradactis McMurrich. 

 But with none of these is there such close correspondence as to induce 

 any considerable assurance. The 6 to 8 dichotomously branched fronds 

 and its habitat in holes and crevices in coral rocks, which Verrill empha- 

 sizes of Lebrunia, have much in common with the species under con- 

 sideration. On the other hand, when he says, "The species examined by 

 me has, on these fronds, at the forks, many more or less spherical bodies 

 having the structure of acrorhagi," there is at once lack of correspondence. 

 And a further comparison of McMurrich 's description of Lebrunia neglecta 

 (Joum. Morph., vol. iii, p. 33) makes it almost certain that the present 

 species can hardly belong under Lebrunia. 



The characters of Oulactis, especially the longitudinal rows of ver- 

 rucas and the more or less circumscribed sphincter, are rather sharply 

 in contrast with the very smooth walls and diffused sphincter of the 

 present species and would seem to preclude this genus from serious 

 consideration. 



As to the genus Cradactis as defined by McMurrich,^ there are also 

 several difficulties. For example, the fronds of Cradactis are defined as 

 "bunches of tentacle-like structures," the walls are dotted with verrucae, 

 and the sphincter is circumscribed. None of these characters is distinc- 

 tive of the present species. But in view of the fact that McMurrich him- 



» Proc. U. S. Nat. Mus., vol. xvi, p. 197. 



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