HYDROZOA — RITCHIE. 833 



Hemir/ct. — The consideration of the relationship existing 

 between the simple free form of this variety' and its more typical 

 form with adnate hydrotliecfe throws some light on the probable 

 origin of Cryplolaria. An example before me illustrates this. 

 A single free hydrothecais growing out from the creeping stolon. 

 At the base of tlie hydrotheca the stolon, leaving the substratum, 

 •curves sliai-|ily round and having reached the stalk of the hydro- 

 theca, clings to, and ascends this, and pnrt of the hydrotheca as 

 "well. The hydrotheca appears now to he adnate, and the erstwhile 

 stolon has become the axial tube. That the latter can assume 

 its original character again is sliown by the fact that the axial 

 tube sometimes terminates as a stolon. The minute space which 

 intervenes bet ween the perisarc of the adnate hydrotheca and 

 that of the axial tube at the base of the inner wall of the former, 

 -and the distinctness of the two skeletal layers, even where they 

 -are adnate, points also to the essential distinctness of hydrotheca 

 and axial tube. 



It would appear, then, that Gryptolaria has arisen from a 

 simple Zct/ora-like stock by the union of a hydrorhizal tube along 

 a hydrotheca to which it just has given rise— -somewhat after 

 the manner of the development of the rhizocaulon of Lafh'ea 

 dibinosa. The regularity of the arrangement of the hydrothecse, 

 And of the branches and branchlets in Gryptolaria, points, how- 

 ever, to a growth less haphnzard than that of the typical rhizo- 

 caulon. The close relationship between Lafoea and Gryptolaria 

 has already been clearly shown by the similarity of tlieir coppinia- 

 gonosomes ; tlie presence in one and the same species of two 

 forms of individuals which, found separately, would have been 

 classified as distinct species of Lafoea and of Gryptolaria, 

 emphasises as markedly this relationship. Yet, although Billard 

 has already slumped these two genera under tlie name of the 

 former, I prefer at present to keep them distinct, on account of 

 the convenience to systematists which their separation into 

 broadly marked groups gives, rather than on account of their 

 natural apartness. 



The reasons which lead me to consider Hartlaub's Gryptolaria 

 confertal as a synonym of G. crassicaulis are given above in the 

 •discussion regarding G. conf^rta. 



Locality. — Station 48, off Wollongong, seven to eight miles 

 from shore ; depth, 55 to 56 fathoms ; bottom, sand and mud to 

 rock; 18th March, 1898; a single colony. 



Dlstrih\dion. — Gryptolaria crassicaulis was described by 

 Allman from specimens obtained ott' Ascension Island at adepth 

 of 420 fatiioms. Since then Hartlaub has described from 

 Antarctic Seas (Lat. 70° 00' S., Long. 80° 48' W., 550 metres) 

 under the name Gryptolaria conferta '?, specimens which seem to 

 me to belong to this species. 



