102 A MONOGRAIMI OF THE TEllTIARY POLYZOA OF VICTORIA. 



3. B. spinifcm, n.sp. PI. XTTT., (1-. 19. 



Zoaiiiiiii fiicmsting. Zocecia broadly ovate or sul)circiilar ; tliyrostome large 

 with about eigbt spines on tlie upper nuiryin, lower lip in young zoteeia straigbt, in 

 older Avitli a large proeess rising from one side and eurved over towards tlie opposite, 

 w Iiieb it nearly meets but leaves a narrow inclostnl sinus ; in many zotecia on one 

 side of the tliyrostome a round avicularium or vibracular pore on a slight eminence. 



M. 



Aspidostoma, H/'ncks. 



Zoariuni l)ilaminate, expanded and foliaceous. Zooccia with the sides tumid, 

 especially in the upper part; tliyrostome at th(^ summit of the zotecium, partly 

 concealed by the tumid border, arched above, straight Ix-low, and protected in front 

 by a broad, shield-like plate or muero which is continued downwards for some 

 distance within the zocccium. 



1. A. crassum, Uincks. PI. XIII., fig. 12. 



Asjridosloma crassum, Uincks, A.M.N. II., Feb., 1881 ; .'' Eschara gigantea. 

 Busk, B.M.C., Pt. IL, p. 91 ; A. glgauteiim, id., C.P., Pt. L, p. 161. 



Zoarium expanded, forming foliaceous expansions contracted towards the base. 

 Zooccia large, ovate or pyriform, separated by grooves, dense sides, especially above, 

 tumid, the front depressed below the tliyrostome, but with a central tumid ridge 

 extending for a short distance downwards ; tliyrostome arched above, straight below, 

 the lower edge with a broad squared plate, witii a thickened margin extending to 

 the sides of the ai)erture, between which and the plate it forms a loop-shaped notch. 

 Ooccia elongated, depressed and flat, minutely granular. 



AV.P. Living between Patagonia and Palkland Islands (llincks) ; Patagonia 

 and Tristan da Cunha (Jiusk). 



Uincks describes the margin of the hood-like border overarching the tliyrostome 

 as rising into two pointed processes with a narrow cleft between. These are not 

 seen hi my specimens, although in some of the zoo'cia tliere is a slight projection on 

 each side wbieli probably represents them worn olV. lie also describes an avicu- 

 larium (absent in the i"ossils) leaning against the side of many of the zotecia a little 

 below the upper (extremity. Dtherwise the recent and fossil forms entirely agree. 

 Busk eonsidiM'ed his own and ilincks' species as identical, but as that admits of some 

 doul)t, I ha\e retained the speciiie name given by Uincks. 



