. The Columella auris in Amphibia. 580 B. F. Kingsbuiy and H. D. Keed, somewhat better understood. Eleven larvae of Spelerpes bislineatus ranging in lengi;h from 15 to 55 mm. were studied by means of serial sections. Just when the columella makes its appearance we can not say, but in larvte 15 and 17 mm. long there is present a deli- cate cord of cells outside the ear capsule extending from the under side of the squamosum towards the fenestral membrane to which it is not closely related at this stage. In a larval Plethodon cinereus (Figs. 6 and 7) of a similar stage of development this cord is
. The Columella auris in Amphibia. 580 B. F. Kingsbuiy and H. D. Keed, somewhat better understood. Eleven larvae of Spelerpes bislineatus ranging in lengi;h from 15 to 55 mm. were studied by means of serial sections. Just when the columella makes its appearance we can not say, but in larvte 15 and 17 mm. long there is present a deli- cate cord of cells outside the ear capsule extending from the under side of the squamosum towards the fenestral membrane to which it is not closely related at this stage. In a larval Plethodon cinereus (Figs. 6 and 7) of a similar stage of development this cord is composed of a greater number of cells and is consequently more com-. Col C. Fig. 8. Spelerpes bisliueatus, larva 23 mm. long. C, artel-ia carotis Interna ; , canalis lateralis ; CoJ., columella ; , cavum perilymphaticum ; , vena petroso-lateralls. pact and larger. Here also, as in Spelerpes, this group of cells is not closely connected with the fenestral membrane. It extends for- ward to the under side of the squamosum and apparently is joined to the ceratohyal by a less marked cord of cells. Figs. 8 and 9 from two sections 25 microns apart may serve to illustrate the extra- otic position of the columella. Comparison with the figures of like stages of Ambystoma and Cryptobranchus is suggested. In Sperlerpes larvse 23 mm. long the lower end of this cord of cells has become intimately associated with the fenestral membrane at the cephalo-ventral margin of the fenestra. At this point the fenes-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Kingsbury, Benjamin Freeman, 1872-1946; Reed, H. D.
Size: 1689px × 1479px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollectionbiod, bookdecade1900, bookyear1909
