THE NAUTILUS. 91 



The authors begin with the new Gasteropod Miratesta celebensis, 

 for the reception of which it seems necessary to establish not only a 

 new genus, but a new family (Miratestidse). The structure, which 

 is briefly described, shows a combination of characters distinctive of 

 various families. The animal is nearest the freshwater Pulmonates, 

 especially the Limnceidae, as is suggested by the Planorbis-l\ke 

 structure of the radula, the nervous system without chiastoneury, 

 the hermaphroditism, and the absence of an operculum. But any 

 very close affinity is impossible, as is shown by the large gills, the 

 very peculiar pouched feelers, and the structure of the shell. Dis- 

 tant relations may, perhaps, be found in the so-called Tbalassophilse 

 (Amphibola and 8iphonaria). In any case, the family is phylo- 

 genetically old, near the base of the freshwater Pulmonates. 



Bulletin 142 U. S. Geol. Survey, 1896, contains a valuable paper 

 upon the geology and paleontology of northwestern Louisiana by 

 T. Wayland Vaughan. A number of new mollusks from Lower 

 Claiborne and Jackson stages of the Eocene are described and fig- 

 ured. 



Mr. Charles Schuchert has given a very useful " Synopsis of 

 American Fossil Brachiopoda, including Bibliography and Syn- 

 onymy " in Bull. No. 87, U. S. Geol. Survey, 1897. The geological 

 distribution, terminology, biological development and classification 

 are discussed, and a valuable chapter contributed by Prof. Charles 

 E. Beecher treats of the morphology of the brachia, a subject which 

 in Beecher's hands has assumed great importance as an index of 

 phylogeny and rank. 



Mr. Felix Bernard has given a very thorough account of the 

 anatomy of Chlamydoconcha Orcutti Ball, in Annales Sciences 

 Naturelles (zool.), iv, 1896, pp. 221-252, with 2 plates. 



A NEW PLICATE UNIO. 



BY BERLIN H. WRIGHT. 



Unio Walkeri sp. nov. 



Shell solid, ovate, inflated at the umbos, rough, plicate-nodulose 

 on posterior slope and indistinctly so anterior to the umbonal ridge ; 

 gradually fading out near the centre of the disk. Umbonal ridge 

 uniformly rounded below and sharply angulate above. Epidermis 

 nearly black ; transmitted light showing a light-colored texture. 

 Very faintly marked anterior to the umbonal angle with broad, 

 widely separated, interrupted rays. Posterior margin bluntly 

 rounded or somewhat disposed to biangulation, uniformly rounded 

 before, dorsum arcuate, base nearly straight or emarginate, cavity 

 uniform, moderate and scarcely extending under the dorsal plate. 

 Teeth solid, single in the right and double in the left valve. Ante- 

 rior cicatrices barely distinct. Thinner behind, showing the plica- 



