320 DIPLURA FRITILLARIA. 



One of the many observations which Steenstrup so liappily correlated in his famous treatise 

 on the ' Alternation of Generations' was made on a little tubularian hydroid which he obtained 

 off the coast of Iceland, and which, with its verticil of pendant medusa-bells, so closely resembled 

 a plant of Fritillaria imperialis, with its verticillate cluster of drooping flowers, that the Danish 

 zoologist gave to it the name of Coryne Fritillaria. 



According to the views, however, by which we must now be guided in our classification and 

 nomenclature of the Hydroida, Steenstrup's hydroid is no Coryne, nor is it referable to any 

 other genus which had, up to the time when Steenstrup recorded it, been described. 



Our knowledge of the trophosome is far from being as complete as could be desired. Indeed, 

 we are not informed whether the hydrophyton is naked or clothed with a chitinous perisarc, and 

 the disposition of the hydranth-tentacles can by no means be inferred with certainty from either 

 the figure or description given by Steenstrup. 



The gonosome, on the contrary, is described and figured with considerable detail, so that no 

 difficulty is met with in obtaining such generic characters as may be aff'orded by this part of the 

 hydroid. 



Some years ago Professor J. R. Green^ discovered in the Bay of Dublin a medusa which so 

 closely resembles that described by Steenstrup as developed from his Coryne Fritillaria that, 

 though nothing is known of the trophosome from which Green's medusa was produced, we are 

 justified in considering it for the present as congeneric with Steenstrup's hydroid. 



Green described his medusa under the generic name of Biplonema ; but as this had been 

 already appropriated by the botanist, he subsequently substituted for it, in a letter to myself, the 

 name of Biplnra. 



It was on these grounds that I had elsewhere' proposed that the name of Biplura Fritillaria 

 should take the place of Coryne Fritillaria. 



'^^^ DiPLURA ruiTiLLAEiA, Steenstrup. 



Coryne Fritillaria, — Steenstrup, Ueber den Generationswechsel, and Ray Society's Trans- 

 lation, p. 27, pi. i, figs. 41 — i6. 

 Steenstrupia Fritillaria, — Agassiz, Cont. Nat. Hist. U.S., vol. iv. 

 DiPLURA Fritillaria, — Allnan, in Ann. Nat. Hist, for May, 1864.. 



TROPHOSOME. — Htduocaulus attains a lieight of about half an incli, slender. 

 Hydranths with five or six tentacles. 



GONOSOME. — GoNOPnouES pendulous, arranged in a verticil of four round the 

 base of the hydranth. Medusfe, at the time of their liberation, in tlie form of a 

 quadrangular bell, with a single rudimental, knob-like, marginal tentacle ; the two 

 tentacles given off from the marginal Inilb of the mature medusa very long and 

 moniliform. 



> ' Ann. Nat. Hist.' for May, 1864. 



