AlCTONARIA. 331 



Taxonomy . — The results of the collection in this respect are not 

 less interesting than are those of the distribution. In the case of one 

 family (the Melithaeidse), a structural character has for the first time 

 come to light, which illustrates the existence of a similar character 

 in other families of this natural but very manifold Order : I refer to 

 the occurrence of two kinds of zooids. In one case (in the same 

 family) it has been found desirable to establish a new genus, and the 

 number of new species is relatively large. The Melithaeidse show a 

 remarkable development here. A remarkable member of the usually 

 rare family Briareidee has been assigned by me to the genus Icili- 

 gorgia, hitherto known only from the West Indies. The number of 

 species of this family found here is relatively large, and includes 

 some rare and very strange forms (SoUnocajdum, Leucoella). Two 

 points of general importance for the family Gorgoniidse may be con- 

 sidered to have been decided by a study of the series which repre- 

 sents the new species, Leptogorgia australiensis, in this collection — 

 1. That colour alone cannot be taken as a character of specific im- 

 portance. 2. That characters derived from the shape, depth, partial 

 presence or absence of superficial grooves in the cortex, or their 

 partial replacement ^by raised lines, as seen in dry specimens, are 

 not of specific, much less of family value, as held by Dr. Gray for 

 some Gorgoniidse (see Catalogue Lithoph. Brit. M.us., 'p. 24,' Elli-' 

 selladce). 



Measurements andTefms employed. — The measurements of spicules 

 are those of average greatest specimens of each form of spicule. I 

 have adopted Verrill's term verruca to signify that specialized part 

 of the cortex which contains the retracted zooid. When describing 

 them I have applied the term longitudinal to the radiating spicules 

 of the verruca, and horizontal to those which are circuljirly arranged 

 with regard to its centre. 



Classification. — I have followed in the main the arrangement 

 adopted/by Kolliker in his ' Icones Histiologicse.' 



ALCYONIID^. 



AxcTONiiir^. 



The absence of both Sarcophytum and Alcyoniwm from the col- 

 lection is perhaps due to the absence of in-shore reefs in the area 

 examined. An Alcyonium was described from. Port King George in 

 Southern Australia by Quoy and Gaimard from the ' Astrolabe ' 

 voyage ; but Lamarck'^ A. putridosum, from that locality, I have 

 ascertained to be a siliceous Sponge. 



