364 



HYDROID^. 



Part IV. 



12th Family. Geryonid^ Esch. (restricted). 



Geryonia Per. and LcS. (non Less.), restricted. — Liriope Less, (non 

 Gegenh.). 

 G. proboscidalis Esch. — Medusa proboscidalis ForsJc. ; M.-Edw., in 

 Cuv. Regn. An., PI. 52, fig. 3. — Geryonia hexaphylla Per. and 

 LeS. (non Br.). — 3Iediterranean (Forskfil). 

 G. hexaphylla Br., PI. 18 (non Per. and LcS.). — Bonin Islands 

 (Mertens). 

 13th Family. Leuckartiu^ Agass} — Geryonidje Esch. (p. p.). 

 Leuckartia Ag. — Geryonia LeticJc. (non Aiict.). 



L. proboscidalis Ag. — Geryonia proboscidalis Leucli. (non Axict.), 

 Arch. Nat., 1856, PI. 1, fig. \. — Nkc (Leuckart). 



* After having satisfied myself that the biten- 

 taculated Medusie thus far referred to the genus 

 Saphenia belong to two different families, Saphenia 

 Forbes to the Nucleiferae, and Saphenia Esch. to 

 the Geryonopsida;, it occurred to me that, among 

 the proboscidal Geryonidiv, there might also be 

 representatives of different families. I was led to 

 this supposition by thp great diversity of types 

 included in that family by earlier naturalists, and 

 even by Forbes. The result of my comparisons 

 are here submitted to the criticisms of those who 

 may have an opportunity of testing the value of 

 my suggestions. That the Geryonopsidie differ from 

 the Leuckartidffi I have no doubt, having had an 

 opportunity of examining several representatives of 

 the two families. But there does not occur, along 

 the American coast, a representative of the Gery- 

 onia proboscidalis of Europe, so that ray inference 

 upon this type are solely based upon a careful com- 

 parison of the descriptions and figures of Forskal, 

 Mertens, Milne-Edwards, Gegenbaur, and Leuckart. 

 On comparing the figures of this species published 

 by Forskal and Milne-Edwards, it may at once be 

 noticed, that, while they agree in every prominent 

 feature, they differ strangely from that of Leuck- 

 art. Gegenbaur's minute description of the same 

 type differs equally from the description given by 

 Leuckart. Gegenbaur says distinctly, " the pro- 

 boscis is characterized by the absence of distinct 

 canals," "its interior forms a large cavity," and "from 



the circular tube arise centripetal, cajcal append- 

 ages." In Leuckart's Geryonia proboscidalis there 

 are no " centripetal appendages ; " moreover, it ap- 

 pears to agree in every respect with the other spe- 

 cies described by him under the name of Geryonia 

 exigua, of which he says, that the " stomach is 

 small, about a line long." He says distinctly, that 

 above the stomach there is " no funnel-shaped cav- 

 ity," and that " the radiating canals arise immediately 

 from it." We have thus Geryonidte, with flat, 

 heart-shaped dilatations of the radiating tubes, as 

 genital organs, which agree with the GeryonopsidsB 

 in the structure of their chymiferous system and 

 its ramification, and others which do not. The 

 latter are Gegenbaur's type, long known from For- 

 skal's description and figure, and for which the 

 name of Geryonida; must be retained ; for the 

 other, first accurately described by Leuckart, I pro- 

 pose the name of Leuckartidie, and to the latter 

 family the genus Liriope Gegenh. (not Less.) also 

 belongs. It will be noticed that the form of the 

 genital organs of the Leuckartidaj is the reverse of 

 that of the GeryonidiE ; the heart-shaped genital 

 organs of the genuine Geryonidoe pointing toward 

 the circular tube, and those of the Leuckartidce to- 

 ward the stomach, while in Geryonopsidaj they 

 extend evenly along the chymiferous tubes, as in the 

 Oceanida;. If I am not mistaken, the true Geryonidaj 

 should be referred to the Discophorie haplostome«, 

 while the LeuckartidM are genuine Hydroids. 



