INVERTEBRATE ANIMALS. 15 



Group 44.— Section GOEGONACE^. Part II. Arborescent. 

 Estimated number of species : recent, 58 ; British, 2. 

 The base of the Gorgonia polype secretes the tough 

 horny elastic stem : another portion of the same polype 

 secretes the soft crust, or bark, which owes its beautiful 

 colour to the presence of calcareous spiculae. 



IT Examples of most of the genera ; but the larger 

 fruticose forms occupy the upper compartment. 



Group 45.— Section PEIMNOACE^. 7rpu>va, the poop of 

 a ship. On the coast of Norway Primnoa is said to 

 attain the height of fifty or sixty feet. Estimated 

 number of species : recent, 13 ; British, 1. 



H Primnoa verticillata from Madeira, presented by 

 J. S. Tyerman. Primnoa lepadifera is a desi- 

 deratum. 



Family ALCYONID^. No solid central axis. 



Group 46.— Sub-family TUBIPORIN^ (Milne Edwards). 

 Estimated number of species : recent, 7 ; British, ; 

 fossil, 



IT Specimens of TuUpora musica, the Organ-pipe 

 coral, and of other species of the genus, from 

 the Indian and Pacific Oceans and the Red 

 Sea. 



Group 47.— Sub-family ALCYONIN^E (Milne Edwards) 

 and allies. Estimated number of species : recent, 

 50 ; British, 3 ; Fossil, 0. 



IT Examples of Spoggodia, and other genera. 

 Coloured drawings of Alcyonium digitatum, 

 with the polypes expanded, and of other species, 

 chiefly after Dana. 



