212 THE VOYAGE OF H.M.S. CHALLENGER. 



Cystous (figs. 1, 2, y). — Each cormidium possesses a single cyston or anal vesicle, 

 attached to the trunk near the base of the siphon. It is smaller than the siphon, but 

 larger than the palpons, and at once distinguished from both by its deep red colour. 

 The cyston is a slender spindle-shaped tube with two slight constrictions and a middle 

 dilatation. This corresponds to the stomach of the siphon, and is densely covered 

 internally with red glandular villi. The granular pigment secreted by these is accumu- 

 lated in a head -like terminal expansion of the distal proboscis, and thrown out by a small 

 terminal opening, the anus. The slender basal pedicle of the cyston bears a simple 

 palpacle, of the same shape as that of the palpon. 



Palpons (figs. .1, 2, ). — The tasters occur in each cormidium nearly in the same 

 mimber as the bracts, ten to twenty or more, besides numerous small buds of young- 

 ones. They are slender cylindrical or spindle-shaped tubules, very extensile and con- 

 tractile, and as in Apolemia have a restless dashing motion. The closed distal end of 

 each palpon is pointed and richly armed with cnidocysts and palpocils. The thinner 

 and pediculate basal end opens into the axial canal of the trunk, and bears a long and 

 thin palpacle (r), similar to that of the cyston. 



Gonodendra. — Each cormidium is hermaphrodite (monocliuic) and bears two 

 clustered gonodendra, a male and a female ; they arise separately from the trunk, both 

 near the base of the cyston. The female gonodendron (fig. 3) is composed of twenty to 

 thirty gynophores, besides numerous small buds. The male gonodendron (fig. 5) is 

 smaller and bears only fifteen to twenty androphores. The umbrella of the gouophores 

 is in both sexes well developed, with four radial canals, and a circular ring-canal on the 

 margin ; the latter bears, at the distal end of the four radial canals, four small tubercles 

 with a red pigment-spot, which are rudiments of reduced tentacles, with a basal ocellus. 

 The gynophores (fig. 4) have a campanulate umbrella and a colourless subspherical 

 manubrium, which contains a single large ovulum, surrounded by spadicine canals. The 

 androphores (fig. 6) have a more oblong umbrella and a club-shaped manubrium of a 

 bright red colour ; its central spadix is surrounded by a thick layer of sperm. 



Genus 40a. Apolemia, 1 Eschscholtz, 1829. 

 Apolemia, Escli., System der Acalephen, p. 143. 



Definition. — Apolemidse with a biserial nectosome, composed of two opposite series 

 of nectophores. Internodes of the siphosome naked. Cormidia polygastric and diclinic, 

 each with several siphons and cystons, and with a single gonodendron, either male or 

 female. Corms dioecious. 



The genus Apolemia was established by Eschscholtz for that North Atlantic form 

 which Lesueur had figured in 1813 under the name Stephanomia uviformis (not 



1 Apolemia — Pacific, A^oKtfias. 



