MIRTH AMKUirAX KAKLY TKRTIARY BRYOZOA. 221 



FLOKIDINA BIFOLIATA, new species. 



Plate 35, fig. 5. 



i/ition. The zoarium is bilamettar with curved fronds. The zooecia are 

 distinct, (mite elongated, separated by a deep furrow; the mural rim is smooth, 

 wide, little salient; the cryptocyst is of little depth, of the same length as the 

 opesium. The opesium is large, trifoliate, elongate; the opercular portion is small 

 and separated from the opesiular region by two, little prominent teeth: the poly- 

 pidian convexity is little salient, non symmetrical. The onychocellarium is larger 

 than the zooecia, quite elongated, fusiform, with spatulate beak; the opesium is 

 oval, the point above. 



Measurements. Opesium |7i<?=0.25 mm. f 7,3=0.50-0.52 mm. 



of zooecia|7fl= 0.20-0.22 mm. m (te= 0.35-0.40 mm. 



Opesium f hon=QAQ mm. f Lon=0.80 mm. 



of onychocellariai lon=Q.ll mm. Onychocellanum, ?w=a30 mm _ 



Affinities. This species has a bilamellar zoarium like Flond'ma granulosa ; 

 it differs from it in the absolutely smooth frontal, and its onychocellarium much 

 longer than the zooecia. 



Occurrence. Lower Jacksonian (Moodys marl) : Jackson, Mississippi (rare). 



Holotype.Czt. No. C3081, U.S.N.M. 



FLORIDINA ONYDENTATA, new species. 



Plate 35, fig. 9. 



Description. The zoarium is unilamellar, creeping over algae. The zooecia 

 are distinct, wide, ogival; the cryptocyst is shallow, concave, oblique to the 

 opesium, finely granulated; the opesium is transverse or trifoliate. The opesiules 

 are nearly complete and linear. The polypidian convexity is very long and often 

 united with the opesial processes. The onychocellarium is larger than the zooecium ; 

 its opesium is triangular and toothed, with a large spine on its proximal border. 



Measurements. Opesium fo=0.14-0.20mm. 7 fZ.3=0.50-0.60mm. 



(including opesiules) 1^=0.20-0.24 mm. a |fe=0.30-0.40mm. 



fZoM.=0.90mm. 



Onychocellarium , 



[7<5?i=0.oOmm. 



Variations. It is probable, that the pivot of the mandible was situated a little 

 above the opesial tooth; this indicates that there were on each side two bundles 

 of mandibular elevator muscles. 



The size of the opesiules is evidence of vigorous parietal muscles, necessary, 

 moreover, for the zoarial hydrostatic system of this robust species. 



We have observed a true zooecium having the form of an onychocellarium. 

 More than once it has been proved that this organ is only a modified zooecium, 

 and that every variation of one occasions a corresponding variation in the other. 



