19i0.] AND INVERTEBRATES OF ST. HELENA. 127 



identified by Dr. Gray and Mr. Saville Kent of the British 

 Museum. The species is evidently identical with that described 

 by S. 0. Ridley, from Ascension, but the name Platygyra is 

 rejected by later writers on the Madreporaria, e. g. Martin Duncan, 

 "Revision of the Madreporaria," Journ. Linn. Soc. xviii. 1885. 

 The latter author admits only one genus, Mceandrina with Gceloria 

 as a sub-genus ; but whether the present species is to be placed in 

 the main genus or the subgenus I have not decided. It is 

 characteristic of the typical Mceandrina that the calycles are not 

 distinct, but united into long grooves with parallel sides from 

 which the septa project ; in the species here considered the 

 calycles are usually distinct, but in many parts, especially in 

 larger colonies, two or three are united, so that they present a 

 stage towards the condition which is typical of Mceandrina, 

 a condition which is really clue to incomplete division of the 

 zooids. 



HYDROZOA and PORIFERA. 

 By R. KlRKPATRICK, F.Z.S. 



HYDKOZOA. 



Family Eudendeiidj. 



EUDENDRIUM CUNNING HAMI, Sp. n. (Plate VII. figs. 1-3.) 



Several specimens are growing out of the sponge C'hondrosia 

 plebeja. The largest example is 9 cm. in height. The growth 

 of the colony is arborescent, with dark horn-coloured fasciculated 

 main stems. The terminal polyp-bearing branchlets have from 

 one to three groups of annular markings between base and 

 summit. 



The few polyps remaining on the specimens are scarcely well 

 enough preserved to enable their characters to be determined, 

 but 24 tentacles were counted in one instance. Nearly all the 

 colonies are female, but one is hermaphrodite. 



The special branches bearing the clusters of female gonophores 

 arise on the upper side of branches or of polypiferous branchlets. 

 The gonophoral branches are shorter than those bearing the 

 nutritive polyps, and funnel-shaped, i. e. they broaden out distally ; 

 sometimes they are annulated throughout, sometimes only on the 

 proximal half. The male sporosacs arise in a double row from an 

 aborted polyp. They are stalked and monothalamic, the stalk 

 curving round and dividing into two lateral wings. 



The ovate gonophores, about 375 /j. in long diameter, are in 

 clusters of 3-8, closely adnate to each other and arranged spirally 

 round a central axis. Each gonophore has a carina around the 

 vertical central plane. When burst the empty sac resembles a 

 hemispherical basket with a handle — the distal half of the carina — ■ 



