REPORT ON THE SIPHONOPHOR^. 263 



description of a North Atlantic species, Physophora borealis, was published in 1877 by 

 Sars (27, Heft hi. Taf. v., vi.). At present it is not possible to distinguish exactly the 

 different species of Physophora described by numerous authors ; a far more accurate 

 anatomical description of the various parts and their arrangement, and a comparison of 

 good figures drawn from nature, is indispensable to render specific distinction possible. 

 Since the genus is not rare, and widely distributed over all seas, it is probably repre- 

 sented by numerous " geographical species." 



Genus 56. Discolabe, 1 Eschscholtz, 1829 (s. str.). 

 Discolabe, Esch., System der Acalephen, p. 155. 



Definition. — Discolabidse with a quadriserial nectosome, composed of four cruciate 

 rows of nectophores. (Siphosome with a single corona of palpons.) 



The genus Discolabe was established in 1829 by Eschscholtz for a Mediterranean 

 Physonect, which was described and figured very incompletely by Quoy and Gaitnard 

 under the name Rhizophysa discoidea (20, Isis, Bd. xxi. Taf. iv. fig. 7). The same 

 authors called it afterwards Physophora discoidea (2, p. 59, pi. i. figs. 21-24). No doubt 

 this Mediterranean form represents some Physophorid or Discolabid, the nectophores of 

 which were detached from the stem ; probably either Physophora hydrostatica (Forskal, 

 11, p. 119) or Physophora tetrasticha (Philippi, 72). This latter possesses four cruciate 

 rows of nectophores and differs generically from the former (with two opposite rows of 

 nectophores). Physophora tetrasticha may, therefore, retain the name Discolabe medi- 

 terranea, given by Eschscholtz. Another closely allied species, taken in the North 

 Atlantic (in the Gulf Stream), may be called Discolabe tetrasticha. A third species, 

 Discolabe quadrigata, inhabits the Indian Ocean, and was observed living by me during 

 my residence in Belhgemma, in December 1881. It is described in the following pages, 

 and figured in Pis. XIX. and XX. Some incomplete but well-preserved corms, taken in 

 the Indian Ocean, which I received from Captain Rabbe (of Bremen), seem to belong to 

 the same species. 



Discolabe quadrigata, n. sp. (Pis. XIX., XX.). 



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



Nectosome (figs. 1-4). — The swimming apparatus has the form of a slender tetragonal 

 pyramid, which is twice as high as broad; its height is 40 mm., the basal breadth 

 20 mm. It is composed of an ovate apical pneumatophore, and of four longitudinal rows 

 of nectophores, which are arranged around the axial trunk in a Inotropic spiral. Each 



1 Discolabe = Discoidal noose or spiral, o/erxoj, X«/3)j. 



