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



Prayidae, and are probably derived from this subfamily of Diphyidae. The two genera of 

 the former correspond to those of the latter. 



Desmalia, the first genus, is in general appearance very similar to Pray a (Pis. 

 XXXI., XXXIL), and possesses, like it, eudoxiform cormidia. Each eudoxome is 

 composed of two medusomes, a sterile and a fertile. The sterile medusome exhibited in 

 the only species observed nearly the same shape as that of Praya galea, figured in 

 PL XXXIL The cavity of the helmet-shaped bract contained a single siphon with a 

 tentacle, and on the ventral side of the former a single gonophore with a well-developed 

 umbrella. All gonophores of the single specimen observed were female. The corm of 

 Desmalia may be, therefore, dioecious. 



Desmophyes, the second genus, is described in the sequel (PL XXX.). It is in 

 general composition and special structure very similar to Lilyopsis, and possesses, like 

 this Prayid, ersseiform cormidia. Each ersseome is composed of two sterile and one or 

 several fertile medusomes. The first sterile medusome consists of a bract (an umbrella 

 with four radial canals), a manubrium (siphon), and a tentacle. The second sterile 

 medusome is represented by a well-developed " special nectophore," a medusiform 

 umbrella with four radial canals and a ring canal, muscular subumbrella and velum, but 

 without manubrium. The umbrellar margin of this Medusa was beset (in the only 

 species observed) with a corona of rudimentary tentacles and ocelli (almost as in some 

 species of Lilyopsis). The group of sexual medusomes was represented by several 

 clustered fertile gonophores ; one large, and a number of small vicarious buds. The 

 corm was monoecious and diclinic, the cormidia alternately males and females. 



The development of the Desmophyidse is not known ; but it will probably be found 

 to be hypogenesis, the gonophores ripening whilst sessile on the stem ; as is also the case 

 in the closely allied Polyphyidse. 



Synopsis of the Genera of Desmophyidse. 



Cormidia eudoxiform, composed of two medusomes (one sterile and one fertile), without 



special nectophore, ......... 32a. Desmalia. 



Cormidia ersaeiform, composed of three or more medusomes, with a special nectophore, . 32b. Desmophyes. 



Genus 32a. Desmalia, 1 n. gen. 



Definition. — Desmophyidse with rounded edgeless nectophores, arranged in a biserial 

 nectosome. Cormidia without special nectophores. 



The genus Desmalia is represented by a polygastric Calyconect, which is in general 

 very similar to the common forms of the well-known genus Praya, but differs from 



1 Desmalia = Marine chain, Uo^k, cb\it;. 



