. Annals of the Carnegie Museum. Carnegie Museum; Carnegie Museum of Natural History; Natural history. Fig. 16. Stropheodonta muscle area to show the two pairs of adductor scars (the small triangles without arborescent mark- ings represent the ante- riors) the low median sep- tum ending in a sort of saddle, and the pustulose ridges, not muscle scars, scars are divided into two elements, the posterior adductors, which are large and oval, and in front of and between these, the small tri- angular anteriors. In front of the muscle scars there is a median septum and on each side of it a rounded pos
. Annals of the Carnegie Museum. Carnegie Museum; Carnegie Museum of Natural History; Natural history. Fig. 16. Stropheodonta muscle area to show the two pairs of adductor scars (the small triangles without arborescent mark- ings represent the ante- riors) the low median sep- tum ending in a sort of saddle, and the pustulose ridges, not muscle scars, scars are divided into two elements, the posterior adductors, which are large and oval, and in front of and between these, the small tri- angular anteriors. In front of the muscle scars there is a median septum and on each side of it a rounded postulose ridge. Outside these ridges are two lower, sharper ridges one of which starts in front of each anterior muscle scar, curves slightly outward, and then in again, but does not approach much nearer the septum than it was at the starting point. These ridges probably have concava \{z\\. Sketch of to do with the brachial apparatus rather than with '''^ cardinal process and the muscular system, as has been previously sup- posed. S. junia Hall. Hall, Pal. N. V., IV, 1S67, p. 108, pi. i8, figs. 3, 4. Only one well preserved specimen of this spe- cies was found in the collection. It is a ventral valve, 44 mm. in length and 50 mm. wide. The hinge is crenulated for three-fifths of the distance on either side of it. Nat- from the beak to the cardinal extremities. The "'"^^ ^'^^? area about the beak is broken, so nothing could be learned about the deltidium or pedicle opening. The scars of the muscles are very well marked. The diductors are large, flabelliform, faintly marked ante- riorly, but with strong posterior ridges extending from the area half way down the sides. Between the diductors are the adductor impres- sions which are divided on the me- dian line by a low, thin septum. These scars are long, narrow and acuminate in front. Two diagonal lines divide the scars into anterior Fig. 17. Slropheodonta junia Hall ; , . , , , , ,,, , , ? , , and posterior elements and the
Size: 1497px × 1668px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., booka, bookcentury1900, bookdecade1900, booksubjectnaturalhistory
