KEPORT ON THE SIPHONOPHORJS. 221 



Genus 41. Stephanomia, 1 Peron et Lesueur, 1807. 



Stephanomia, Peron et Lesueur, Voyage aux terres australes. 



Definition. — Agalmidas with a short and rigid siphosome, the trunk of which is 

 scarcely contractile. Bracts with small intervals. Corrnidia ordinate, with free inter- 

 nodes, in a single, straight, ventral series. Tentdla with a simple terminal filament. 



The genus Stephanomia is the oldest known form of Agalmidse, and was founded in 

 1807 by Peron for an Australian Physonect, of which his collaborator Lesueur has left 

 an excellent picture (14, pi. xxix. fig. 5). The figure represents the siphosome only, 

 without the nectosome ; but fortunately I had the opportunity during my residence in 

 Ceylon (in December 1881) of examining a complete living specimen of a closely allied 

 species. The cylindrical siphosome of this Indian Stephanomia nereidum had exactly 

 the same form as that of the Australian Stephanomia amphitrites in Lesueur's figure, 

 except the special form of the bracts ; these are all tridentate in the latter, and 

 arranged very regularly in four longitudinal series ; whilst in the former they were 

 provided partly with three, partly with five teeth, and arranged in six less regular 

 series. The long internodes between the corrnidia were free, and the yellowish 

 gonostyles attached near the base of the red-coloured siphons. The biserial nectosome 

 composed of twelve complete nectophores, had nearly the same form as that of Crystal- 

 lodes vitrea (PI. XVII. figs. 1-3). The position of the quietly swimming animal was 

 the same as in Lesueur's figure, the trunk lying horizontally and the corrnidia forming 

 a rectilinear series on its ventral side ; the siphons and tentacles, therefore, depending 

 vertically. The same position is exhibited also by the similar Agalmid, which Huxley 

 afterwards described as Stephanomia amphitrites (9, pi. vi.); but this has loose corrnidia, 

 and belongs probably to Phyllophysa (Genus 43). 



Genus 42. Crystallodes, 2 Haeckel, 1869. 



Crystallodes, Hkl, Entwickelungsgeschichte der Siphouophoren, p. 43. 



Definition. — Agalmidse with a short and rigid siphosome, the trunk of which is 

 scarcely contractile. Bracts with small intervals. Corrnidia ordinate, with free inter- 

 nodes, in a single, straight, ventral series. Tentilla tricornuate, with a terminal ampulla 

 and two paired horns. 



The genus Crystallodes was established by me in 1869 for an Atlantic Agalmid, 

 the complete anatomy and ontogeny of which I observed in January and February 1867, 

 during my residence in the Canary Island Lanzerote (84, p. 43, Taf. vi.-xiii.). Another 

 closely allied species, differing from the Atlantic Crystallodes rigida mainly in the 

 special form and arrangement of the bracts, was examined by me fifteen years after- 



1 Stephanomia = Corona, aTtQivufta. 2 Grystallode$ = Crystal-shaped, ^votx^oZyis- 



