586 Canon A. M. Xoiman — Xoles on the 



Genus Electra, Lamouronx_, 1834. 



Type, Elect)' a veriicillata, Lamouroux. 



See Norman, "Month on the Trondhjem Fiord," Ann. & Mag-. Nat. 

 Hist. ser. 6, vol. xii. p. 113. 



With respect to tlie synonyms I gave in tlie place referred 

 to :— 



1st, Ampkiblestrum, Gray. All that I wrote in the note 

 is, I believe, correct ; but I have since examined the speci- 

 mens in B. M. which Gray had named A. membranacea, 

 Abild., and find that they are not that species, but the 

 Ampkiblestrum Fleminyii, Busk. It seems to me therefore 

 that the specimens should take precedence of the name erro- 

 neously given to them by Gray, and that the genus Amphibles- 

 trum may be used in the sense in which Busk employed it, 

 for although he makes no reference to the matter, he no 

 doubt had himself examined these specimens in the British 

 Museum. 



2nd, Conopeum. I have re-examined the specimens in 

 B. ]\I. referred to this genus and find them, as I stated then 

 from long memory, to be M. Lacroiocii. If it should be deemed 

 therefore at any time desirable to use a separate genus for 

 that species, Conoptum is ready for the purpose. 



This genus is not furnished Avith pore-chambers. At one 

 time I was inclined to unite in one species M. Lacroixii, 

 Audouin, and M. munostaclajs, Busk. They often occur 

 together on the same oytter or other large shell, mingled in 

 such a way as to be puzzling ; but I am now satisfied as to 

 their specific difference. I may here mention that I have 

 failed to observe in any northern specimen examined by me 

 such a back with lucid spots as that represented by Waters 

 in his paper on the Membraniporidse, pi. xlviii. figs. 14, 15, 

 or such an operculum as he refers to M. Lacroixii ^ ; but I 

 do see on most specimens examined the two processes at the 

 distal extremity, which look as though they were for muscular 

 attachment. The following I regard as some of the specific 

 differences between E. monostac/iys and E. Lacroixii: — 



Electra monostachys. Typically there is a single spine at 



* I am indebted to Dr. Levinsen for a very interesting form of 

 E. monostachi/s from Denmark which has a calcareous operculum, hut 

 of quite a different form from that figured by Waters and attributed to 

 Lacroxii. I subsequently sent to Dr. Levinsen specimens of our Britisli 

 var. fossaria, Hincks, and he found them to agree with his variety 

 from Denmark in having calcareot(s opercula &c. I may say that with 

 respect to figures given by Levinsen in the ' Zoologica Dauica, Mosdyr,' 

 1894, I should refer his ligs. 37, 38, 40 to E. monostachys and tig. 3'j to 

 jEJ. LacroUii. 



