4. PUSTFLOPOKA. 21 



The small size, delicate structure, and the absence of brown spots 

 amply suffice to distinguish this species from Pustnlopora ansfralis. 

 But it is not so easy to define the characters by -which it is distin- 

 guished from F. prohoscidea or P. dejiexu. The chief arc its peculiar 

 mode of growth in a minute polyzoarium composed usually of a 

 stem dividing into two branches, each of which again divides into 

 two short ramules; and it never seems to go beyond this stage of 

 growth. 



2. Pustulopora australis, Busk. (Plate XTII. a. left figure.) 



Zoarium branched dichotomously ; branches short, incrassated, 

 truncate ; cells almost entii'ely immersed or about half free ; surface 

 minutely papillose, summits of papillae of a dark brown or black 

 colour. With age the walls become much thickened and porcella- 

 neous, with transverse rugoe. 



Pustulopora australis, Bk. T\nj. Rattles, i. p. 350. 



Hah. Bass's Strait, 45 fathoms, and elsewhere in the Australian 



3. Pustulopora parasitica, n. sp. (Plate XYII. figs. 1, 2.) 



Zoarium about a quarter inch high, usually formed of 1-3 branches, 

 short and truncate ; cells usually deeply immersed, and very slightly 

 prominent, except in very young specimens. Colour brown, with 

 white spots. 



Hah. Bass's Strait, 45 fathoms ; New Zealand. Always parasitic 

 upon a species of Catenicella. 



4. Pustulopora prohoscidea, E. Forbes. (Plate XVII. a. right 

 figure.) 



" Zoarium slender, branched alternately ; cells slightly projecting, 

 four completing a whorl." 



Pustulipora prohoscidea, Johnst. 2ud ed. p. 278, j^l. 48. figs. 4-4; 



Gray, List B. Bad. p. 

 Entalophora prohoscidea, D'Orb. Pal. Firing, p. 780. 

 Pustulopora prohoscidea, M.-Edw. I. c. p. 27, pi. 12. fig. 2 ; Heller, 



I. c. p. 125; Gruhe, Die Insel Lussin, p. 68. 



Hub. Shetland seas {E. Forhes) ; Mediterranean {M.-Edw.) ; 

 Adriatic {Heller Sfc); Teneriffe and Canaries (HOrh.); Madeira 



(j.r.j.). 



The occurrence of this species is not noticed either by Mr. Norman 

 among the Shetland forms, nor does any species of Pmtidopora 

 appear in Professor Smitt's lists of Scandinavian or Arctic Polyzoa. 

 It may therefore by chance have been erroneously referred to Shet- 

 land by E. Forbes, as it appears to be a Mediterranean and Atlantic 

 form. 



