1 896.] BiirrlSH Htdsoids and mbdtjs^. 495 



TEACHOMBDUS^. 

 Fam. GbetonidjE. 



LlEIANTHA APPBNDICOT.ATA (Porbes). 



Geryonia appendiculata Forbes (1848). 

 lAriope appendicnlata, Gegenbaur (1856) ; Agassiz (1862). 

 Xanthea appendiculata, Haeckel (1864). 

 Liriantha appendiculata, Haeckel (1879). 

 This medusa was exceedingly abundant at Plymouth during the 

 whole of September and the early part of October, 1893. As 

 most of the specimens belonged to the early stages, I was able to 

 trace its development. 



First Stage. — Umbrella sub-globose, from 1 to 2 mm. wide, and 

 about as long. Velum very broad. On the margin of the 

 umbrella there are four interradial tentacles, about half the length 

 of the umbrella, and are usually carried in au upright position 

 alongside the ex-umbrella. On the inner side of these tentacles 

 there are rows of uematocysts, which are directed outwards when 

 the tentacle is alongside the umbrella. These tentacles remain 

 throughout life. On the ex-umbrella, about one-third the distance 

 from the margin, are situated four little, perradial, primary 

 tentacles ; each consists of a large cluster of nematocysts upon a 

 short stalk. Within the bulb containing the nematocysts there is 

 a fine whip-like tongue, which I have seen occasionally protruded 

 and after moving rapidly about in every direction withdrawn again 

 inside the. bulb. These primary tentacles disappear later in life. 

 The characteristic features of this stage are the primary perradial 

 tentacles and the absence of a manubrium. 



Second Stage. — During this stage the manubrium commences to 

 grow downwards, a continuation of the edge of the circular 

 opening in the first stage. At the same time four perradial 

 tentacles commence to grow from the margin of the umbrella. 

 They differ considerably from the interradial tentacles, and are 

 not carried in an upright position, but hang down or trail behind 

 the umbrella when the medusa is in motion and can be extended 

 to a considerable length. Each tentacle has numerous rings of 

 nematocysts. The lateral primary tentacles on the umbrella are 

 usually present, but one or two may be absent. Medusse belonging 

 to this stage may be characterized by possessing four perradial 

 tentacles on the margin of the umbrella, and a short manubrium, 

 not reaching to the velum. Umbrella about 3 mm. in diameter 

 and colourless. 



Third Stage. — This is really the commencement of the adult 

 stage, asthe gonads begin to develop upon the radial canals. The 

 lateral tentacles disappear and small scars mark their former 

 position upon the ex-umbrella. The manubrium extends slightly 

 beyond the cavity of the umbrella. Umbrella about 4 njm. in 

 diameter. 1 have divided, the early stages into these ^ three 



