REPORT ON THE SIPHONOPHOR^E. 251 



corm, whilst they form a closed bilaterally compressed calyx in the rapidly swimming 

 animal. 



Palpons (q). — The corona of palpons, which is placed immediately beyond the corona 

 of bracts in the Nectalidse, is comparable to that of the Anthophysidse as well as of the 

 Discolabidae. The number of palpons, however, is much smaller than in the last two 

 families, and seems not to exceed that of the superjacent bracts. It may be that each 

 palpon and the appertaining bract originally composed a medusome, the former 

 representing its manubrium, the latter its reduced umbrella. The distal end of the 

 tubular, very mobile palpons, seems to possess a mouth-opening (fig. 2, qo), and in this 

 case they should be called cystous. Palpacles or tasting filaments were not observed. 



Siphons (s). — The large polypites of Nectalia exhibit distinctly the four usual 

 segments, a short pedicle, a basigaster with very thick wall filled by cnidocysts 

 (figs. 2, 13, sb), a stomach sm). the inside of which bears longitudinal rows of glandular 

 villi (sv), and a very extensile and contractile proboscis with a thick muscular wall (sr). 

 The distal mouth of the latter is four-lobed (so). 



Tentacles (t). — The long tubular tentacle which is attached to the base of each 

 siphon bears a series of numerous tentdla. The cnidosac of the latter includes in 

 Nectalia a strong, spirally-twisted cnidoband, and bears at its distal end a simple terminal 

 filament ; the latter is replaced in Sphyrophysa by an odd terminal vesicle and two 

 lateral horns. The difference between the two genera is therefore sinular to that 

 between Stephanomia and Agalma, or between Halistemma and Agalmopsis. 



Gonophores. — The corms of Nectalia are monoecious and the corrnidia monoclinic, 

 since two clustered gonodendra, a male and a female, are attached near the base of each 

 siphon. The medusoid gonophores are very small and numerous, and have a reduced 

 umbrella. As usual, the spermaria are oblong or spindle-shaped, the ovaria roundish 

 or subspherical. 



Genus 54a, Nectalia, 1 Haeckel, 1888. 

 Nectalia, Hkl., System der Siphonophoren, p. 41. 



Definition. — Nectalidas with a biserial nectosome, composed of two opposite rows of 

 nectophores. Cnidosacs of the tentUla with a simple terminal filament. 



The genus Nectalia, as the type of this family, is represented by the North Atlantic 

 species figured in PI. XIII. It is similar to Physophora, but differs from it essentially 

 in the corona of large bracts which separates the biserial nectosome and the flower-shaped 

 siphosome. The cnidosacs of the tentilla bear a simple terminal filament. 



The single specimen of this genus which I have examined, and which is described in 

 the secmel, I captured by scooping it up with a glass vessel without touching it, on 



1 Nectalia = Swimming in the sea ; nixr^, ahiog. 



