REPORT ON THE ALCYONARIA. 141 



with a broadened web-like expansion at the origin of each of the twigs. The nutrient 

 canals as in Plexaura. 



The spicules of the ccenenchyma are as follows :— First tlie foliaceous clubs, which 

 measure 0'3-0'2G ; 0'2-0'18 ; 0"2-0-l ; Oi 8-0'2 mm. The foliaceous portions are broad 

 and short with a wavy outline, the root-like processes are spreading and very spiny. 

 The spiny spindles are small, 0-3-0-04 ; 0-24-0-04; 0-12-0-04 mm. The tri- and 

 quadriradiate forms are few and have not the characteristic form generally to be found 

 in the species of this genus, they measure 0'2-0"l ; 012-01 mm. The curved and 

 straight needle-shaped spicules found in the tentacles are 0'2-0'02 ; 0'l-0'02 mm. 



While in the structure of the axis this species must be referred to Plexaurella, yet 

 it would seem to differ in several respects from all the hitherto described forms ; and the 

 spicules seem intermediate between those of Plexaura and Plexaurella. It must however 

 be conceded that there is a great deal of uncertainty as to the species which should be 

 placed under these genera, and a careful examination of all the types of Esper, Milne- 

 Edwards, and Verrill will be needed ere this question can be properly settled. 



Klunzinger ^ suggests that Plexaiirella should be placed near to Juncella, which no 

 doubt in the structure of its axis it somewhat resembles, but pending a thorough 

 revision of the group it seems more advisable to leave it in the family Plexauridse. 



Habitat. — Station 208, January 17, 1875, Philippine Islands; depth, 18 fathoms. 



Genus Pseudoplexaxira, n. gen. 



Professor KoUiker emended the diagnosis of the genus Plexaura, having separated 

 first therefrom the species forming the new genus Plexaurella, by ibrming two sections, 

 called by him "duraj" and " molles," which differed in the nature of the .coenenchyma, 

 in the former large spindle-like spicules being found, while in the latter the coenenchyma 

 is soft, thick, and friable without the large spicules. In both the outer layer is composed 

 of club-shaped or spiny spicules of various shapes. In the present genus the axis is 

 horn)^ with a central calcareous portion, the outer layer of coenenchyma is soft and when 

 dry friable ; the inner layer contains a number of light purple or violet coloured irregu- 

 larly stellate spicules or spindles with few rays. The following diagnosis will help to 

 distinguish it from Plexaura. 



The colony is but feebly branched ; the axis horny, in the older portions solid ; in the 

 younger and terminal portions the centre is partially filled with calcareous particles. The 

 coenenchyma is thick and membranous, the outer layer is white, friable ; in older portions 

 the outer layer of spicules gets rubbed off, leaving a soft membrane in which the polyps 

 are embedded, but in the younger portions there is a well-marked layer of colourless spindle- 

 shaped spicules. The polyps are placed close to one another in a somewhat regular spiral 



' Die Kor.iUthiere des rolhen Meeres, Th. i. p. 59. 



