78 THE OCEANIC HYDROZOA. 



Fam. PHYSOPHORIAD^. 

 Genus PHYSOPHORA [Eschscholz). 



Coenosarc dilated at its distal end ; provided below the pneumatophore with necto- 

 calyces. No hydrophyllia. Hydrocysts forming a series on the proximal side of the 

 polypites. A spheroidal involucrum completely inclosing the sacculus. 



Physophora (sp. ?) PI. VIII, figs. 1—12. 



The anatomy of certain species of Thysophora has been studied of late years by Philippi,' 

 Vogt, and K511iker. Only three specimens presented themselves during my voyage, and 

 neither of these was an adult, while two were exceedingly small. Nevertheless, as I paid 

 particular attention to points which happen to have been comparatively neglected by Vogt 

 and KoUiker, I trust that the additions which I am able to make to their account of this 

 interesting genus will not be without value. 



The hydrosoma in the largest of Vogt's specimens measured rather more than two 

 inches in length, and Kolliker's appear to have had about the same dimensions (2^ inches). 

 In my largest specimen the hydrosoma was only three quarters of an inch long.^ 



The coenosarc enlarges above into the pyriform pneumatophore ; below this it is slender 

 and cord-like, and gives attachment to a variable number of nectocalyces. Its inferior 

 extremity is enlarged, and supports the remaining appendages. 



With regard to the structure of the pneumatophore, Kolliker states only that it has 

 an apical pigment-spot ; and Vogt appears to me not to have comprehended its organization 

 at all, inasmuch as, in his description of the adult Physophora, he mistakes the walls of 

 the pneumatophore for those of the pneumatocyst, having apparently overlooked the latter.^ 

 This is the more singular as, in his account of the young Physophora, at p. 58, he states that 



' Ueber den Bau der Physophoren und eine neue art derselben, Physophora tetrasHcha. 'Miiller's 

 Archiv.,' 1843, pp. 59—67, tab. v. 



- Peron and Lesueur's P. muzonema is stated to have been four inches long; the P. Forskdlii. 

 of Quoy and Gaimard two inches ; while Forskal's original P. hydrostatica had a length of only 

 an inch and a half. The axis of Philippi's P. tetrasticha had apparently a length of about 

 two inches. 



' La bulle d'air est entouree immediatement comme je viens de le dire, d'uue expansion muscu- 

 laire faisant suite aux couches musculaires du tronc" (p. 43). Philippi denies the existence of any air 

 in the pneumatophore (p. 63). 



