12S 



THE VOYAGE OF H.M.S. CHALLENGER. 



I. Subfamily 



SPH-ERONECTID.E. 



Nectophore heinispheri- - 

 cal or mitriform, with 

 rounded surface, with- 

 out sharp edges. 



II. Subfamily 



CYMBONECTID.E. 



Nectophore pyramidal, 

 with five prominent 

 sharp edges. 



Synop>sis of the Genera of ' Monophyidae. 



Hydrcecium a ventral groove of the nectophore, incompletely 

 closed by two overlapping wings, ..... 



Hydrcecium a complete cylindrical canal in the ventral wall 

 of the nectophore, with a basal opening, .... 



Hydrcecium wanting. Nectophore protected by a cap-shaped 

 dorsal bract ; between them is the siphosome, 



Hydrcecium a ventral groove of the nectophore, incompletely 

 closed by two overlapping wings. Bracts spathiform, 



Hydrcecium a complete coni- 

 cal or campanulate cavity 

 in the ventral wall of the 

 nectophore. 



Bracts of the cormidia coni- 

 cal or spathiform, with a 

 deep ventral fissure, . 



Bracts of the cormidia cu- 

 boidal, with six square 

 faces and a basal cavity, . 



18. Monophyes. 



19. Sphxronectes. 



20. Mitrophyes. 



21. Cymhonectes. 



22. Muggixa. 



23. Cymha. 



Genus 18. Monophyes, 1 Claus, 1874. 

 Monophyes, Claus, Die Gattung Monophyes, &c, 70, p. 29. 



Definition. — Monophyidse with a rounded, edgeless, mitriform nectophore, and an 

 open hydrcecial groove on its ventral side ; the latter includes the siphosome. which is 

 incompletely protected by two overlapping lateral wings. Bracts mitriform or hemi- 

 spherical, with rounded surface and a simple phyllocyst. 



The genus Monophyes was founded in 1874 by Claus for two different Mediterranean 

 species of Calyconectse, which bear a single mitriform nectophore on the top of the stem. 

 One of these two species, Monophyes gracilis, belongs to the following genus Sph&ronectes, 

 which possesses a closed tubular hydrcecium, open only at the distal end. The other 

 species, Monophyes irregularis, may be retained as the type of the present genus ; it 

 differs from the former in the bilateral arrangement of the four radial canals of the sub- 

 umbrella, and mainly in the shape of the hydroecium, which is not a tubular canal, but 

 an open groove or infundibular cavity. 2 This peculiar character is more developed in 

 two other species, which I have myself observed, Monophyes princeps, from the Indian 

 Ocean (PL XXVII. figs. 13, 14), and Monophyes hydrorrhoa, from the Atlantic Ocean 

 (Canary Islands). The hydrcecial groove extends here along the whole ventral side of 

 the bilateral nectophore, and its two edges are prominent as two free wings, one of which 

 overlaps the other more or less. The Atlantic species (Monophyes hydrorrhoa) is very 

 similar to a small Mediterranean form figured in 18S5 by Chun, who supposed it to 



1 Monophyes = Single animal (fiovoipvyis) ; Calyconecta with a single nectophore. 



2 70, p. 32, Taf. iv. figs. 16-18. 



