378 BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



HIPPOPORELLA MULTILAMELLOSA. new species. 



Plate 48, figs. 18-22. 



Description. The zoarium is free and forme'd of many lamellae superposed 

 on the same side; the base in contact with the subjacent algae presents some hexa- 

 gonal zooecia striated transversely and sometimes perforated. The zooecia are 

 distinct, hexagonal, separated by a very salient thread; the frontal is smooth, 

 convex, ornamented with some lateral areolae. The aperture is elongated; the 

 anter is almost circular and separated by two very salient cardelles from a poster 

 rectilinear exteriorly and concave interiorly. The ovicell is large, globular, salient, 

 imbedded in the distal zooecia; it opens above the aperture and can not be closed 

 by the operculum. The avicularium is large, transverse, without pivot; it is placed 

 on the frontal irregularly. 



Measurements. Aperture JAa=0.13 mm. . f 3=0.50 mm. 



(exterior) Ua=0.10-0.11 mm. Us=0.35-0.40 mm. 



Variations. In the interior (fig. 21) the two cardelles are represented by 

 two transverse condyles, somewhat salient. The avicularium is most character- 

 ized by its mandible lodged in a calcified area, spatulate in form and of little depth ; 

 the orifices which serve as passage for the retractor and extensor muscles of the 

 mandible are separated or joined together. The frontal is a compact olocyst per- 

 forated simply by some lateral areolae. 



Affinities. In its exterior aspect and its multilamellar zoarium, this species 

 may be confounded with Dalcaria brevis. It differs from the latter in its aperture, 

 of which the anter is rectilinear, in its hexagonr,! and much larger zooecia and in 

 its ovicell imbedded in the distal zooecia. 



It differs from Hippoporella perforata in its smaller micrometric measure- 

 ments and in its inferior face, where all the zooecia are not regularly perforated. 



Occurrence. Middle Jacksonian (Castle Hayne limestone) : Wilmington, 

 North Carolina (common). 



Cotypes.Cnt. No. 64075, U.S.N.M. 



HIPPOPORELLA PERFORATA, new species. 

 Plate 86. figs. 7-13. 



Description. The zoarium creeps on algae forming orbicular lamellae, free 

 and irregular. The zooecia are hexagonal, very little elongated, distinct, sep- 

 arated by a furrow ; the frontal is smooth and convex : it is an olocyst perforated 

 laterally by some large areolae. The aperture is semilunar, transverse; two deep 

 cardelles separate a large anter from a small rectilinear poster. The ovicell is 

 very large, imbedded in the distal zooecium and is hyperstomial. It opens above the 

 aperture by a large opening without connection with the operculum. On the lower 

 face of the zoarium the zooecia are convex, hexagonal, perforated in front of the 

 aperture by a round pore, and striated transversely. The ancestrula is membrani- 

 poroid. 



