NOKTH SIDE OF THE BAY OF BISCAY, AUGUST, 1906. 19 



BIMERIA, Wright, 1859. 



Generic character. Trophosome — hydrocaulus well developed, 

 usually erect and branching ; hydrantlis fusiform. Gonosome — 

 gonophores in the form of sporosacs developed upon the hydrophyton. 



The above description of the genus is almost identical with that 

 given by Torrey (1902), who has emended Hincks's description and 

 broadened it, so as to include the genus Garveia. According to Allman 

 and Hincks, Bimeria is distinguished from Garveia by the perisarc, 

 covering the lower part of the hydranth, extending over the proximal 

 half of each tentacle, a character more suitable for a species than for 

 a genus. 



1 am distinctly in favour of constituting the genus Bimeria in such 

 a manner that it may stand in relation to Bougainvillia as Coryne 

 does to Sijncorync, the trophosomes of the two genera being some- 

 what similar, but their gonosomes quite distinct, the former possess- 

 ing sporosacs and the latter planoblasts. 



It must be remembered that Bimeria vcstita is the type species 

 of the genus. Its trophosome in general appearance is very much 

 like a Bougainvillia. Madame Motz-Kossowska (1905) has, however, 

 transferred Bimeria vcstita to the genus Pcrigonimus, which, like 

 Bougainvillia, reproduces by means of planoblasts. The planoblasts 

 of Perigonimus and Bougainvillia are not all alike, in fact they 

 belong to two distinct medusoid families. 



It would be an advantage to place rruvotclla grisea, Motz-Kossowska 

 (1905), in the genus Bimeria. The generic character of Pruvotella, as 

 given by Madame Motz-Kossowska, should make an excellent specific 

 character. 



I certainly prefer to place Hydroids, like Bougainvillia, with plano- 

 blasts, and Hydroids, like Bimeria, with sporosacs into separate genera, 

 though there may be a few cases in which it is hard to draw the 

 line. I notice that naturalists who have confined their attention 

 solely to the trophosome completely disregard the nature of the 

 gonosome in their classifications. They consider it is a matter of no 

 importance whether the gonosome is a planoblast or a sporosac, and 

 ignore the fact that medusae have also a system of classification. I 

 am strongly of the opinion that the gonosome should play an impor- 

 tant part in the classification of Hydroids, especially in those Hydroids 

 which liberate free-swimming medusae. 



Bimeria (Garveia) nutans (Wright). 

 This Hydroid occurred at Station I., 75 fathoms, on Sertularella 

 folyzonias, and at Station II. it was common on Sertularia ahietina. 

 The colonies are without gonophores. 



