212 



On a Species of Siphonophore observed at Plymouth. 



By 



J. T. Cnnniughaiu, H.A. 



Last autumn tlie occurrence of a small Siphonopliore in the produce 

 of the surface tow-nets attracted my attention. I first noticed it in 

 the contents of a small net^ worked five miles south of the Eddystone, 

 on September 12th, and afterwards it was obtained in great abundance 

 close to the Plymouth Breakwater, and even inside the Sound. It 

 was brought in numbers to the Laboratory almost every day up to 

 about the middle of October, but after the end of that month it was 

 not seen again. 



This Siphonophore was a Monophyid, and its single nectocalyx was 

 from 3 to 6 or 7 mm. in length. Its appearance as a whole when 

 slightly magnified is represented in Figs. 1 and 2, p. 213. 



An elaborate description of the organism would be impossible 

 without a detailed explanation of the structural features which are 

 common to the family Monophyidge, and which distinguish that 

 family from other divisions of the Siphonophora. Such a detailed 

 explanation would be quite superfluous, since a reference to Haeckel^s 

 Report on the Challenger Siphonophora, p. 125, and elsewhere, will at 

 once afford a lucid and definite analysis of the whole class, and 

 enable anyone to follow the discussion of the identity and position of 

 the species here considered. I shall therefore confine myself to the 

 question of identification, using the terms adopted by Haeckel for the 

 various organs. 



It will be seen at once, then, that the form belongs to the genus 

 Muggisea, the definition of which is " Monophyidse with an angular 

 pyramidal nectophore, and a complete infundibular hydroecium in its 

 ventral side. Bracts spathiform or conical, with a deep ventral 

 groove, a bevelled basal face, and a simple ovate phyllocyst.^' I 

 have not figured the bracts, nor have I been able to make a thorough 



