FLOBIDAN BRYOZOA. 43 



the zocecial aperture and commonly placed one at each side of this, obliquely directed 

 distally and outwards: these are the characters, which distinguish the most typical 

 state of Hippothoa spongites from the other forms of this group. But from this state, 

 even in the PouRTALEs-collections, it shows the usual variations of almost all its cha- 

 racters. The more outgrown colonies, and, particularly, the new layers of zooecia, 

 which are growing över the older ones, get their front side more convex. The harder 

 calcifications va&y get the pores in this front side closed, what variation will occur in 

 the same colony with the open pores. Proximally of the aperture, the zocecia, in the 

 middle of their front side, very often get a raised, more or less acute tubercle (mucro). By 

 the thickening of the front wall, the aperture, secondarily may be sunken in a circular 

 depression. The size of the zocecial aperture varies to 0,n or 0,12 mm. Still more 

 the avicularia may vary both to their place, number and size. It is not uncommon to 

 find a single aviculariuin on the zooecia, of a varying size, at the one side of the 

 aperture, but more usual, especially in the feebler calcifications, retaining their most 

 typical size, they may occur as many as four on the front side, proximally of the aper- 

 ture, of each zooecion. Occasionally, in the harder calcifications, we find great, spathulate 

 avicularia, sometimes bent in a crescentic manner, irregularly dispersed över the colony. 



The rounded, swollen ooecia, in the same manner, are placed free and irregularly 

 distributed över the zooecia. They lack the pores in the wall; very often they are 

 crowcled by avicularia of a varying number and size. As to their own varying size, 

 their breadth very commonly ecpials that of two zocecial rows. 



Through the above-named variations of the constitution of the front wall of the' 

 zooecia, the Hippothoa spongites very nearly approaches the Hippothoa ansata (— Hipp. 

 alba [Hincks] *), and, through the secondary sinking of the aperture of the zocecia, it 

 shows its near relationship to the Hippothoa Woodiana "'). This last peculiarity, in 

 connexion with the not uncommon variation of the length of the zocecial aperture, 

 places at its side, also, one Floridan form, which scarcely, specifically, will be distin- 

 guished from the Hippothoa Dutertrei 3 ); but, as it presents one peculiarity in the form 

 of the vibraculum, it may well have its own name, 



Hippothoa pes anseris (Pl. VII, figs. 159 and 160). 



Char.: Zocecia rhombico-ovalia frontem imperforatam, convexam, aperturam (cujus 

 latitudo = 0,08 mm.) semiellipticam vel potius elongato-semicircularem, margine incras- 

 sato setis septem munito circumvallatam, margine proximali sinuato delicatissime den- 

 tatam praabent. Vibracularium ad latus utrumque aperturas zocecii vibraculum prasbet 

 fissum, cujus raclii tres in pedis avis palmati formam membrana colligantur. Ocecia 

 parva sunt, tumide rotunda. 



Hab.: Nullipora? affixam hane formami e prof. 42 org. cepit Pourtales. 



') See Busk, Qnart. Journ. Micr. Se. vol. VIII, Zoophytol., tab. XXX, figs. 2 and 2, a. The text I have 

 never seen. 



2 ) Lepralia Woodiana, Busk, Crag Polyzoa, p. 42, tab. VII, figs. 1 and 3. 



3 ) Flustra Dutertrei, Aud., Sav. Beser, de VEgypte, Polypes, tab. IX fig. 2; D'Orb. ( Reptescharellina) Pal. 

 Franc. Terr. Gret , vol. V, p. 453. 



