KEPOET ON THE SIPHONOPHOBiE. 113 



Its superior or proximal half has four smooth edges, is pyramidal, and forms a prominent 

 ventral crest. Its inferior or distal part is a quadrilateral prism with four strong serrate 

 edges, prominent below as four three-sided pyramidal apophyses, the two dorsal far 

 larger than the two ventral (fig. 11). 



Canal of the Gonophores (fig. 17, cp). — This is long, peduncular, and divides at the 

 apex of the subumbrella («') into four rather regular radial canals (cr). These exhibit an 

 elegantly pinnulated appearance, produced by alternately prominent small diverticula. 

 They are connected at the base of the large velum (v) by a circular canal (cc). 



The ovaria (fig. 17, o), as well as the spermatia (figs. 9-14, Inn), are spindle-shaped 

 manubria, which hang freely in the upper half of the umbrellar cavity of the gonophores. 

 They contain a large central cavity (spadix). 



Genus 14. Amphiroa, 1 Blainville, 1834. 

 Amphiroa, Blainville, Manuel d'Actinologie, p. 133. 



Definition. — Eudoxidas with a bilateral, prismatic bract, bounded by five odd trape- 

 zoidal faces and two paired pentagonal faces. Phyllocyst composed of an ovate de- 

 scending dorsal sac, and two slender horizontally diverging lateral canals at its apex. 

 (Eudoxiae of the genus Abyla.) 



The genus Amphiroa (PL XXXVI.) comprises those monogastric Eudoxidae which 

 arise from the polygastric Diphyid genus Abyla (Genus 29, PI. XXXV.). Its bract has 

 a peculiar and very complicated form, which may best be compared with a prompter's box. 

 It is composed of two four-sided prisms, which are united at right angles. The vertical 

 prism covers the dorsal side of the Eudoxia, and is nearly filled up by a very large sac- 

 shaped phyllocyst. From the apex of the latter arise two divergent lateral canals which 

 run horizontally in the second prism, covering the apical face of the Eudoxia. 



The genus Amphiroa was first observed and named by Lesueur (probably in 1803), 

 but first published from his drawings by Blainville, in 1834. 2 Avery accurate description 

 of it was given in 1859 by two excellent observers, Huxley (9, p. 64) and Gegenbaur 

 (10, p. 17). These two authors, independently of each other, arrived at the same 

 opinion, that Amphiroa is the free Eudoxia of Abyla trigona. The latter, therefore, 

 called it Eudoxia trigonse. We retain this name for the Mediterranean species, whilst 

 Amphiroa alata of Huxley is the Eudoxia of Abyla alata, inhabiting the Tropical 

 Pacific and Indian Ocean. A third species, described by Huxley as Amphiroa angulata 

 (9, pi. v. fig. 2), is probably the Eudoxia of Abyla leuckarti, Huxley. Different from 

 these three species is Amphiroa carina, which occurred in a bottle in the Challenger 

 collection, taken at Station 348. I myself observed this species living, and detaching 

 itself from Abyla carina, in February 1867, in the Canary Islands. 



1 Amphiroa, ' Aptpiga, a daughter of Okeanos. '-' 24, p. 133, Atlas, pi. iv. tig. 1. 



(ZOOL. CHALL. EXP. — PART LXXV1I. — 1888.) Hllhll 15 



