. Bulletin - United States National Museum. Science. EASTERN PROVINCE INTERIOR REGION SPECIES. 283 TRIODOPSIS, Raf. Animal heliciform, mantle posterior, other characters as in Patula. Shell imperforate or nmbilicated, orbicularly depressed or subglobose, more or less obliquely striated; fig 301. whorls 5-7, the last somewhat de- flexed in front; aperture sinuously coarctate, subtriangular; jteristome white, thickened, broadly and an- gularly reflexed, usually dentate; Animal of t. paiuata. parietal wall of the aperture with a strong, obliquely entering denticle. The subgenus inhabits almost ex
. Bulletin - United States National Museum. Science. EASTERN PROVINCE INTERIOR REGION SPECIES. 283 TRIODOPSIS, Raf. Animal heliciform, mantle posterior, other characters as in Patula. Shell imperforate or nmbilicated, orbicularly depressed or subglobose, more or less obliquely striated; fig 301. whorls 5-7, the last somewhat de- flexed in front; aperture sinuously coarctate, subtriangular; jteristome white, thickened, broadly and an- gularly reflexed, usually dentate; Animal of t. paiuata. parietal wall of the aperture with a strong, obliquely entering denticle. The subgenus inhabits almost exclusively ISTorth America, especially the Eastern Province. Two Central American species have, however, been described, and one European species, personata, Lam. This last is said by Moquin-Tandon to have 3-5 separated ribs upon its jaw, while our American sj)ecies, as shown below, have numerous ribs. Jaw stout, arcuate, low, wide, ends but little attenuated, blunt; cut- ting margin without median projection; anterior surface with numerous decided, separated ribs, denticulating either margin. There are about 15 in palUata ; 10 in obstricta ; 15 in appressa ; 14 in inflecfa; 10 in Rugeli; 14: in faliax ; over 10 in Eopetonensis ; 17 in Van Nostrandi; 14: in introferens ; over 12 in vultuosa ; 11 in loricata ; * over 10 in tridentata. Triodopsis does not differ from Mesodon or Polygyra in the character of its jaw. Stenotrema, on the other hand, is readily distinguished by having the ribs broader and more crowded on its jaw. The general arrangement of the teeth on the lingual membrane is as in Patula. The characters of the individual teeth are given on Plate VII of Terr. Moll., V. I have selected appressa (Plate VII, Fig. Q) to show these characters, comparing the dentition of the other species with it. The centrals are longer than wide; the base of attachment has its outer, lower, lateral expansion but little developed, its lower margiu incurved, its upper margin squarely reflect
Size: 1457px × 1715px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorun, bookcentury1800, bookdecade1870, booksubjectscience
