. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. 66 ANNALS OF THE SOUTH AFRICAN MUSEUM. Fig. 9. Anagaudryceras cf. cassisianum (d'Orbigny). The holotype of Gaudryceras salinarium Douville (after Douville 1931). xl. No. D H W W/H Ui SAM-PCA2769 39 15 (38) 18 (46) 1,20 ? J5 28 8(29) 12 (43) 1,50 13 (46,4) JJ 22 6(27) 10 (45) 1,70 11 (50) Discussion D'Orbigny's syntypes (Fig. 8) show the following features: the shell is evolute (umbilicus 41-45% of diameter), with a wide, shallow umbilicus, evenly rounded umbilical shoulder, slightly convex flanks, an
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. 66 ANNALS OF THE SOUTH AFRICAN MUSEUM. Fig. 9. Anagaudryceras cf. cassisianum (d'Orbigny). The holotype of Gaudryceras salinarium Douville (after Douville 1931). xl. No. D H W W/H Ui SAM-PCA2769 39 15 (38) 18 (46) 1,20 ? J5 28 8(29) 12 (43) 1,50 13 (46,4) JJ 22 6(27) 10 (45) 1,70 11 (50) Discussion D'Orbigny's syntypes (Fig. 8) show the following features: the shell is evolute (umbilicus 41-45% of diameter), with a wide, shallow umbilicus, evenly rounded umbilical shoulder, slightly convex flanks, and a rounded venter. The whorl section is almost circular, about as wide as high. On the inner whorls, extremely fine lirae arise at the umbilical seam and pass forward (prorsiradiate) to the umbilical shoulder where they increase by bifurcation and intercalation. On the flanks the lirae are initially prorsiradiate, but quickly recurve so as to become rectiradiate or slightly rursiradiate on the ventral half of the flanks. There are periodic collars which follow much the same course as the constric- tions. On the outer whorls, the lirae become coarser and Gaudryceras-like, nar- rower than the interspaces, while collars split into coarse lirae on the flanks. Gaudryceras salinarium Douville is based upon a fragmentary specimen with a circular whorl section, and showing broad Anagaudryceras-likc flank ribs on which are superimposed Gaudryceras-\ike lirae (Fig. 9). Thus, the holotype of G. salinarium appears to differ from A. cassisianum only in what appear to be the broad flank ribs typical of mature Anagaudryceras. Of the new material from the Salinas locality, a large fragment (Fig. 10J) appears indistinguishable from d'Orbigny's species, but lacks the broad flank ribs of G. salinarium, while the juvenile (Fig. 11B-D) differs in possessing a depressed whorl section and very indistinct collars. Neither d'Orbigny's nor Douville's species are well known and the differences are well
Size: 1706px × 1464px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectnaturalhistory, booky
