REPORT ON THE SIPHONOPHORiE. 243 



medusomes is again composed of three corresponding organs, viz. . a manubrium (a siphon, 

 a cyston, or a palpon), an appertaining filament (tentacle or palpacle), and a corona of 

 bracts (corresponding to the umbrella of the original medusa). The two sexual medu- 

 somes, or rather clusters of medusomes, are represented by two gonochoristic bunches of 

 gonodendra, a male and a female ; they arise separately from the common base of the 

 cormidium, from the basal insertion of the long pedicle of the polypites ; the male bunch 

 is smaller than the female. The form and structure of the single parts are essentially the 

 same as in the closely allied Forskalia ; but the internodes of the trunk, between the 

 equidistant cormidia, are covered only with bracts. Strobalia therefore exhibits a 

 similar relation to Forshalia as Anthemodes does to Halistemma, or Crystallodes to 

 Agalma. A beautiful species of this genus, Strobalia cupola, was observed living by 

 me in the Indian Ocean, and wdl be described in my Morphology of the Siphonophorse ; 

 a fragment of a similar species, Strobalia conifera, was collected by the Challenger in 

 the South Pacific (Station 288). 



Genus 51. Forskalia, 1 Kolliker, 1853. 

 Forslcalia, Kolliker, Die Schwimmpolypen von Messina, p. 2. 



Definition. — Forskalidaj with loose cormidia and segmented trunk of the sipho- 

 some. Gonodendra monostylic, arising from the trunk, separate from the siphonal 

 pedicles. Siphons with hepatic ridges. Nectosome without palpons. 



The genus Forskalia, hitherto the only representative of this family, comprises in the 

 definition here stated those forms, the well-known type of which is the Mediterranean 

 Forskalia contorta, Leuckart (8), probably identical with Forskalia edivardsii of 

 Kolliker (4). The trunk of the siphosome is in this species, as well as in Forskalia 

 tholoides described in the sequel, distinctly segmented or articulate, with equidistant 

 annular constrictions, from which the single medusomes of the loose cormidia take 

 origin. Usually three different medusomes arise separately from the stem between 

 every two siphons, viz., (l) a sterile cyston with a palpacle; (2) a sterile palpon with a 

 palpacle ; and (3) a sexual palpon, to the base of which is attached a clustered monostylic 

 gonodendron (with female gonophores on the proximal part and male gonophores on the 

 distal part). But sometimes the number of palpons is multiplied (often two or three 

 arising from a common pedicle), and their arrangement is more irregular. Another 

 difference between Forskalia and Forskaliopsis is seen in the presence of palpons in the 

 nectosome of the latter, wanting in the former. The general appearance of Forskalia is 

 more delicate and similar to Strobalia and to Agalmopsis. Probably to this genus 

 belong a number of different species inhabiting the warmer seas, e.g., Stephanomia 

 atlantica of Fewkes (44) ; but their distinction requires a further accurate comparison. 



1 Forskalia, named in the honour of the celebrated naturalist, Petrus Forskal (1775). 



