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



Phyllocyst (fig. 13, be). — The canal system of the bract is composed of three parts 

 of a large ovate phyllocyst (be), a short peduncular canal, and a long dorsal csecum. 

 The small peduncular canal arises from the common stem (a), and runs immediately to 

 the ventral base of the large ovate phyllocyst (be). This latter is placed in the apical 

 half of the bract, and contains in its uppermost part a spherical oleocyst (eo). Its 

 rounded apex does not reach the apical crest (nk). The dorsal canal (cd) is a slender 

 caecum, which arises from the base of the phyllocyst. and runs along the dorsal median 

 line of its cavity, separated from it by a thin jelly-plate. The dorsal canal is therefore 

 spur-shaped and crooked, concave on the ventral, convex on the dorsal side. Its blind 

 lower end does not reach the basal edge (ng). 



Siphon (fig. 12, s). — The polypite or siphon is suspended in the top of the subum- 

 brellar cavity of the bract, and may be completely hidden in it. From its short 

 pedicle arises the tentacle (t). A pyloric valve separates the thick basigaster (sb) from 

 the stomach, which exhibits eight yellow striae hepaticfe. The proboscis (sr) is very con- 

 tractile ; its mouth exhibits sixteen short indentations. 



Tentacle (fig. 1 2, t). — The single tentacle of the siphon is distinctly segmented by 

 numerous constrictions, and from each constriction arises a tentillum. The pedicles (ts) 

 and the terminal filaments (tf) of the tentilla are long and slender. The reniform 

 cnidosac exhibits on its convex side six to eight longitudinal rows of medial cnidocysts 

 (fig. 16, km), on both sides of its base a group of large spindle-shaped lateral cnidocysts 

 (kg), and at the distal end a group of small pyriform cnidocysts (kp). 



Gonophores (fig. 12, h; fig. 15). — The sexual Medusa which arises from the stem 

 at the ventral side of the siphon, has a four-winged umbrella, which is pyramidal in the 

 smaller apical half, prismatic in the larger basal half. Its four prominent and denticulate 

 wings are unequal in pairs in the younger gonophores, the two dorsal wings (fig. 12, hit) 

 being much larger than the two ventrals ; afterwards (fig. 15) they become nearly equal. 

 A long peduncular canal (fig. 1 5, cp) runs through the pedicle of the umbrella to the top 

 of the subumbrella («'), and divides here into four equidistant radial canals. The spindle- 

 shaped spermaria of the male gonophore (fig. 12, hs), and the ovate or subspherical ovaria 

 of the female (fig. 15, o), occupy the apical half of the subumbrellar cavity. 



Genus 16. Aglaisma, 1 Eschscholtz, 1829. 

 Aglaisma, Eschscholtz, System der Acalephen, p. 129. 

 Definition. — Eudoxidae with a bilateral prismatic bract, which is cuboidal in the larger 

 upper part, obliquely pyramidal in the smaller lower part. Phyllocyst with four cruciate 

 radial canals, two odd sagittal (an ascending and a descending) and two paired lateral 

 canals. (Eudoxiaj of the genus Calpc.) 



1 Aglaisma, dyhaiafnt^Omaxaeat 



