58 THE OCEANIC HYDROZOA. 



conical, terminating in a rounded apex. One face — tlie anterior — is excavated in its superior 

 half by a wide and shallow groove, which is continued into the wide cavity which occupies 

 the inferior half, and which has somewhat the form of a pyramid with a truncated apex. 

 The posterior wall of the cavity is tolerably thick, and terminates below in a short, 

 transversely truncated margin. The lateral walls of the cavity become very thin at their 

 anterior margins, which are cut away from above downwards and backwards. The right- 

 hand margin slopes gradually into the inferior edge of the posterior face. The left-hand 

 margin, on the other hand, cuts the edge at an obtuse angle, which is produced into a point. 



The phyllocyst is about two thirds as long as the interval between the apex of the 

 hydrophyllium and that of its inferior cavity. It is usually broad at the base, tapers 

 to an obtuse point above, and has no lateral processes. Its walls are largely vacuolated. 



The calyx varies a good deal in size and proportion. It is a little convex anteriorly and 

 posteriorly, and its edges are sharply serrated ; superiorly and posteriorly it is prolonged 

 into a short process traversed by a canal which divides into the ordinary four radiating 

 canals a little below the apex of the nectosac. 



Length of the hydrophyllium, one fifth of an inch. Length of the calyx, one fifth of an inch. 



Eudoxia Lessonii is one of the commonest of Diphyozooids. I took it in all the seas 

 which the " Rattlesnake " traversed in her circumnavigatory voyage, and it appears to be 

 common in the Mediterranean and Adriatic. 



Eschscholz characterised the genus Eudoxia ('Isis,' 1825, and 'System') thus: "Tubulus 

 suctorius unicus. Pars corporis organa nutritoria fovens simplex (cavitate natatoria haud 

 instructa);" a definition which will apply equally well to any Diphyozooid whatever. 



In the 'System' another genus, .£Vscb«, immediately follows. It is defined, " Tubulus 

 suctorius unicus. Pars corporis nutritoria cavitate parva natatoria, tubuli instar prominenti, 

 instructa." And Eschscholz states that the only distinction between Frscea and Eudoxia 

 is the presence in the former, of a very small swimming cavity, which projects like a short 

 tube from the nutritive piece, or hydrophyllium. Of this genus he makes two species, 

 E. Quoyi and E. Galmardi. 



On comparing Eschscholz's figures and descriptions with the various states in which T 

 have observed Eudoxia Lessonii, I entertain no doubt that his two Erscea are merely Eudoxia 

 Lessonii with differently developed calyces. 



I have found it to be the rule in this species that there should be a single large calyx, 

 devoid of any manubrium, and, consequently, presenting the appearance of an ordinary 

 nectocalyx, while one or two much smaller gonocalyces containing manubria, with ova 

 or spermatozoa, are attached to the pedicle of the polypite. Sometimes there were two such 

 large empty calyces. 



It was the constancy with which these empty calyces occurred which, more than 

 anything else, led me to believe the monogastric Eiplnjdm to be independent existences ; 

 and it may still be a question whether these empty calyces are all gonocalyces whose manubria 

 have discharged their contents and disappeared, or whether they are sometimes or always 

 true nectocalyces.' 



^ Consult on this point Leuckart's excelleut history of Eudoxia campanula {=Lessonii}, iu Z. U., 

 p. 43. 



