134 THE VOYAGE OF H.M.S. CHALLENGER. 



That author observed only a single nectocalyx, and supposed that it might be a young 

 and imperfect Diphyes. But I find the same form in different bottles from the 

 Challenger, taken in the Pacific, and also in the collection of Captain Eabbe. One 

 nectophore only (the first or proximal) is always present, whilst there is no trace of a 

 second or distal nectophore. I am therefore convinced that this form is a true 

 Monophyid, not a Diphyid, and this the more as the peculiar character of this group is 

 yet more distinct in another Indian species, Cymbonectes huxleyi ; I observed this 

 species, described in the following pages, during my stay in Ceylon. A third species, 

 Cymbonectes cymba, inhabits the Atlantic Ocean, and will be described afterwards. 



Cymbonectes has no complete hydroecium, but an open infundibular groove on the 

 ventral side of its nectosac ; it agrees in this respect with the genus Monojihyes 

 (sensu stricto, compare p. 128), but it differs from this in the pyramidal form of its 

 angular nectophore. 



Whilst in Belligemma I succeeded in observing the development of the fertilized egg 

 of Cymbonectes huxleyi ; it is very similar to that of Galeolaria aurantiaca, described 

 by Metschnikoff (84, Taf. vi., vii.). The four most important stages of it are figured in 

 PI. XXVII. figs. 9-12. 



Cymbonectes huxleyi, n. sp. (PI. XXVII. figs. 1-12). 



Habitat. — Indian Ocean; Belligemma, Ceylon, December 1881 (Haeckel). 



Nectophore (fig. 1, lateral view from the right side ; fig. 2, dorsal view ; fig. 3, ventral 

 view ; fig. 4, transverse section through the middle part). — The single nectocalyx is 

 helmet-shaped or slenderly campanulate, 6 to 7 mm. long, 2 to 3 mm. broad ; it is some- 

 what broader in the upper than in the lower half. The exumbrella has five prominent, 

 elegantly denticulate edges which unite above in the pointed apex, and end below in the 

 median crests of five triangular teeth surrounding- the basal mouth. 



The five edges of the nectophore are arranged as in Diphyes, one odd running along 

 the dorsal median line (near the nectosac), two lateral corresponding to the two lateral 

 canals of the latter, and two ventral forming the edges of the hydrcecial canal. From 

 the base of these latter arise in the lower half of the nectophore two broad triangular 

 wings, the larger left of which overlaps the other and thus incompletely closes the 

 hydrcecial groove (fig. 4) ; the free edges of these wings are strongly dentate (fig. 3). 

 The bases of the wings are continued above the basal ostium of the nectophore, and here 

 form on its ventral side two broad ovate basal lobes with elegantly denticulate edges. 

 These lobes support the siphosome proceeding from the basal mouth of the hydrcecial 

 canal. 



Nectosac (fig. 2, iv). — The subumbrellar cavity is ovate, twice as long as broad, and 



