SYNCORYNE SARSII. 275 



medusa-bearing forms present such differences in their gonosomes that it is impossible to 

 comprise them all under a single genus. 



I believe that our descriptive zoology of the IIydroida will be best served by retaining the 

 name of S/jncoryne, though in a more restricted and definite sense than that in which it has been 

 generally employed. We shall thus avoid a further complication of synonymy, and preserve 

 a sufficiently expressive and convenient name. 



I shall thus employ Ehrcnberg's uame of Si/nconjne for those hydroids which with a 

 coryniform trophosome possess a gonosome which is referable to the form described above under 

 the character of the genus.' 



Among some species of the genus Syncorijne we find the very exceptional condition of the 

 planoblast never detaching itself from the trophosome, although its well-developed umbrella com- 

 pletely fits it for free locomotion. Under these circumstances the manubrium becomes loaded with 

 generative elements, sometimes to such an extent as completely to fill the cavity of the umbrella, 

 Avhile the marginal tentacles remain imperfectly developed. This condition of the planoblast is 

 precisely that which is presented by the gonopliores of certain Siphonopuora. 



*^* 1. Syncoutne Sarsii, Lovcn. 



Syncoryne Sarsii, — Loven, in Transactions of the Kojal Swedish Academy of Sciences, 1833, 

 translated in Wiegmann's ArcLiv, 1837, p. 323, tab. vi, fig. 

 25. Sars, Fauna lit. Norv., p. 3, tab. i, figs. 1 — 6. 



TROPHOSOME. — Hydrocatjltjs rising to the height of half an inch, slender, 

 sparingly branched, nearly smooth. Hydkanths with from twelve to sixteen 

 tentacles. 



GONOSOME. — GoNOPHORES developed among the tentacles on the body of the 

 hydranth. Manubrium with the margin of the mouth slightly crenulated ; marginal 

 tentacles set with round wart-like clusters of thread-cells, and having a brownish-red 

 ocellus in their bulbous bases. 



Colour. — Hydranths pale rose colour, manubrium of medusa clear red. 



Development of Gonosome. — May and June. 



Habitat. — On Laminaria and other sea-plants. 



Batki/metrical distribution. — Laminarinn zone. 



Localities. — Island of lloroc. Coast of Norway (Sars) ; The Cattegat (Loven). 



I have never met with this species myself, and have drawn up the above diagnosis from Sars's 

 description of a Norwegian hydroid which he refers to the Syncoryne Sarsii, figured and so 



' I have already defined the genus Sijncoryne in the sense here explained, " On the Constructiou 

 and Limitation of Genera among the Hydroida," 'Ann. Nat. Hist.' for May, 18G1. 



3G 



