98 GEOLOGY AND PALEONTOLOGY OF THE WEST INDIES. 



Occurrence. Oligocene (Emperador limestone), old quarry one-third 

 mile north of west of Empire, Panama Canal Zone, D. F. MacDonald 

 and T. W. Vaughan, collectors, 1911 (loc. No. 6016) ; Oligocene (Anguilla 

 formation), southwest side of Crocus Bay, Anguilla, Leeward Islands, 

 T. W. Vaughan, collector, 1914 (loc. No. 6894); lower Miocene (Bow- 

 den marl), Bowden, Jamaica (common). 



Geological distribution. Miocene of Australia and New Zealand 

 (Waters). 



Habitat. Atlantic off Florida; Pacific off Australia. Specimens have 

 been dredged off Australia to a depth of 121 meters. Smitt in Florida 

 has discovered them between 40 and 56 meters, but Osburn states that 

 the species abounds at a depth of 24 meters. 



Family CONESCHARELLINIDJE Levinsen, 1909. 

 Genus STICHOPORINA Stoliczka, 1862. 



Stichoporina tuberosa, new species. 

 (Plate 1, Figures 20 to 23; Plate 6, Figures 16 to 19; Plate 7, Figures 1 to 8.) 



The following is a description of this species : 



The zoarium is free, conical, hollow, with very thick walls. The peri- 

 stome is salient, ornamented with small tuberosities; it bears one or two small 

 elliptical avicularia with bar or denticles. The apertura is elliptical, elon- 

 gated, hidden at the base of a short peristomie ; it is formed of a large semi- 

 elliptical anter and of a small concave poster, separated by two small, salient 

 cardelles. The ovicell is large, somewhat salient, convex; it is hyperstomial 

 and always closed by the operculum. A salient, elliptical avicularium, with 

 two denticles serving as pivot, is placed at the base of each zocecium; it 

 deforms the adjacent peristomes. The inner side is tuberose and bears very 

 large pores arranged in quincunx. On the lower face there are large pores 

 surrounded by very small ones. 



Measurements. Apertura :ha = Q. 14 mm. , la = 0. 10 mm. ; zocecium : Lz = 0.30 

 mm., Zz = 0.30 mm.; opesium of avicularium: /io = 0.10 mm., Zo = 0.06 mm;, 

 avicularium: Z/at; = 0.20 mm., lav = 0.12 mm. 



This is a very elegant species characterized by its peristomial 

 tuberosities. The ancestrula is visible only in the interior of the 

 zoarium; it is covered exteriorly by the first zocecia. All the zocecia 

 are separated from each other by small canals which appear to end in 

 the large, inferior pores. 



The oral tuberosities are hollow. The pores of the internal cavity 

 are avicularia of which the pivot is formed by two denticles; they are 

 analogous with those of the external face (inferior). 



The internal face (and upper) bears also large cavities which we 

 believe to be hydrostatic cavities; but it must be proved that the 

 ectocyst is resistant enough to confine an equal amount of water. We 

 must suppose also that these cavities are intended to counterbalance 

 the irregularities of calcification and to assure the perfect equilibrium 

 of the zoarial system. 



