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



spathiform bract, and hidden in its cavity a siphon with its tentacle. The fertile 

 medusome, placed at the ventral side of the former, is a medusiform gonophore, either 

 male or female. 



Bract (figs. 5, 6, b). — The protecting rudimentary umbrella or hydrophyllium is 

 similar to that of Diphyes, spathiform, or irregularly conical, with a deep ventral fissure, 

 and an obliquely truncate base. Its structureless jelly-plate is very thin in the lower 

 half, thick in the upper half, which encloses a large pyriform phyllocyst. This contains 

 large vacuolate entoderm cells, and an oil-globule in its apex. The truncate base of the 

 bract has four corners, two ventral smaller and two dorsal larger triangular lobes. 



Siphon (figs. 5-7, s). — The single polypite which is attached on the top of the sub- 

 umbrellar cavity of the bract has the formation usual in the Calyconectse, a short pedicle, 

 an ovate basigaster with very thick exoderm, full of cnidocysts (sb), a utricular stomach 

 with thick entoderm (sm), and a very protractile proboscis (sr) ; the distal mouth- 

 opening of the latter may be expanded in form of a circular suctorial disc (fig. 5, ss). 



Tentacle (figs. 5-7, t).- — The single tentacle which arises from the pedicle of the 

 siphon is of medium size, and bears a row of ten to fifteen or more tentilla. Each of 

 these lateral branches bears upon its club-shaped pedicle a reniform cnidosac (fig. 8, km). 

 This includes on its convex side about four to six longitudinal rows of smaller paliform 

 cnidocysts, and at its base, on both sides, three very large ensiform cnidocysts ; the 

 terminal filament (tf) is usually coiled up, and armed at the distal end with a hemi- 

 spherical group of pyriform cnidocysts, provided with long cnidocils (kp). 



Gonophores (figs. 5, 6). — The sexual medusoids alternate regularly in the cormidia, so 

 that each two neighbouring ones form together a di clinic pair. The male eudoxomes (fig. 6) 

 are nearly of the same shape as the female (fig. 5). Each gonophore is an ovate or club- 

 shaped sac, placed at the ventral side of the siphon. The rudimentary umbrella, which 

 possesses the usual four radial canals, and the uniting marginal canal, embraces closely 

 the manubrium. The spadix or central canal is large in the spermaria (fig. 6, hx), small 

 or rudimentary in the ovaria (fig. 5,f). 



Genus 22. Mnggisea} Busch, 1851. 



Muggixa, Busch, Wirbellose Seethiere, &c, 67, p. 48. 



Definition. — Monophyidse with an angular pyramidal nectophore and a complete 

 infundibular hydroecium on its ventral side. Bracts spathiform or conical, with a deep 

 ventral groove, a bevelled basal face, and a simple ovate phyllocyst. 



The genus Muggisea was founded in 1851 by Busch (67, p. 48) for a Mediterranean 

 Monophyid, which Will had figured seven years before under the name DijJiyes kochii 

 (65, p. 77, Taf. ii. fig. 22). The identity of these two forms was demonstrated in 1882 



1 Muggisea = Inhabitant of the port of Muggia, near Trieste. 



