490 jiu. p, T. BuowNB ON [Mar. 17, 



variabile, Haeckel, consists of several distinct species, one of them 

 being Phialidiimi (Eitcojae) vai-iabile (Claus), a species probably 

 identical with Phialidmm huskianum (Gosse). 



Bohm (1878) has given Campamdina acuminata as the name 

 of this species, which he has described and figured in the adult 

 stage, taken off Heligoland, Bcihm has not reared the medusa 

 from the hydroid, and does not show that the young medusa from 

 the hydroid Campanulina acuminata develops into the medusa 

 which he has described under the same name in the adult condition. 

 No doubt the young medusae from the hydroid Campanulina 

 acuminata do develop into one of the species belonging to the 

 genus Phialidium. For this reason I have not used Bohra's specific 

 name of the adult medusa, as it may not belong to the hydroid 

 Campanulina acuminata. 



I give here a description of the various stages of Phialidium 

 temporarium : — 



1st Stage. Four tentacles. (Plate XVII. fig. 4.) — The earliest 

 free-swim ming stage, which I have seen, was taken at Valencia 

 in May 1895. Umbrella bell-shaped, about | mm. in length and 

 width. Four perradial tentacles and four interradial tentacle-bulbs. 

 Eight marginal vesicles with a single otolith in each. Tentacle-bulbs 

 and the basal bulbs of the tentacles yellowish brown. Stomach 

 short ; mouth with four short lips. In one specimen the apical 

 stalk, or the prolongation of the stomach into the substance of the 

 umbrella, was still present, indicating that the medusa had not 

 long been liberated from its hydroid. The generative organs form 

 a minute round or oval swelling, one on each radial canal, about 

 halfway down. 



2nd Stage. Eight tentacles. — The interradial bulbs belonging to 

 the first stage develop tentacles, and a little later some of tiie 

 adradial bulbs begin to appear. It may be sometimes diflicult to 

 distinguish at this stage this species from Phialidium cymhaloideum, 

 as both possess eight marginal vesicles, but in the latter species I 

 have always seen at least two otoliths in all the vesicles. In 

 Phialidium temporarium occasionally two otoliths may be present 

 in one vesicle, but never in all the vesicles. 



3rd Stage. Sixteen tantacles and IG or more marginal vesicles. — 

 The adradial tentacles appear in no definite order, so that one 

 quadrant sometimes contains more tentacles than another. The 

 marginal vesicles also increase in number, one is always present 

 between every two tentacles, occasionally two may be present. 

 The umbrella grows faster in width than in length, being about 6 

 to 7 mm. in width and 4 to 5 mm. in length. The generative 

 organs grow downward towards the margin and become oval- 

 shaped. The colour of the generative organs shows slight variations, 

 usually yellowish brown, occasionally reddish brown. 

 . Adult Stage. (Plate XVII. figs. 5 & 6.)^The largest specimen 

 which I have measured was 21 mm. in width and 11 mm. in length, 

 with 38 tentacles. Two or three marginal vesicles between every 



