380 



BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



The species belonging to this genus are : 



Hippomenella (Mucronella) perforate/, Maplestone, 1902. Recent, Australia. 

 IHippomenella (Lepralia) pcrlstomata Waters, 1899. Recent, Madeira. 

 Hippomenella (Lepralia) miicronelliformis Waters, 1899. Recent. Madeira. 



E F G 



FIG. 115. Genus Hipixjfinnclla, new genus. 



hippopus Smitt, 1S67. A. Ordinary zooecia, magnified. B. Upper part of a 

 xooeduni, showing the aperture and two triangular hinge teeth. C. Zooecia with ovate avicu- 

 laria. D. Zooecia and zooecia with sutural lines. E-H. Opercula. (A G after Levinsen. 1916; 

 H after Waters.) 



Hippomenella (Petmlia) convene/ Canu. 1013. Lutetian. 



Hippomenella (Petralia) mucronata Canu. 1913. Lutetian. 



Hippomenella (Lepralia) semilevis Reuss. 1869. Priabonian. 



This genus, of which we describe 15 new species, is a very natural one; the 

 examination of our plates reveals no aberrant type. Un- 

 fortunately, on account of an extraordinary polymor- 

 phism, the determinations are exceedingly difficult, and 

 the classification of these species has given us great 

 trouble. 



A singular anomaly is the disappearance of the 

 genus in the recent waters off Florida, where no species 

 has been cited by Smitt in 1872, or by Osburn in 1914. In 

 Europe the genus made its first appearance in the Lute- 

 tian in the vicinity of Bordeaux; it occurs fossil in the 

 Priabonian, and it still exists at Madeira. It is correct 

 to say that it is extremely rare, for only the type of 

 Waters species exists in the Funchal Museum. 



This genus is intermediate between Hippoporina 

 Neviani, 1895, and Peristomella Levinsen. 1902; it con- 

 tains some species which in their exterior aspect have exactly the appearance of 

 species of the latter genus, but they are provided with cardelles. 



A v25 



FIG. 116. Genus Hippomen- 

 ella Canu and Bassler, 1917. 

 A, B. Hippomenella mucro- 

 nelliformis Waters, 1898. A. 

 Zooecium with its avicularia 

 and areolae, X 25. B. Oper- 

 culum, x 85. (A, B after 

 Waters, 1S9S.) 



