. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. 406 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY exceedingly like that of the closely related j^ounger species R. plaesiourus. Protaspis (PL 3, figs. 1-5; Text-fig. 4) subspherical in shape, excluding spines maximum length mm., maximum width mm., maximum height mm. Cephalon and protopy- gidium subequal in size. Occipital ring of width (tr.) about one-third total width, defined posteriorly by shallow ring furrow, anteriorly by extremely faint occipital furrow, and set off from pleural region by its convexity
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. 406 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY exceedingly like that of the closely related j^ounger species R. plaesiourus. Protaspis (PL 3, figs. 1-5; Text-fig. 4) subspherical in shape, excluding spines maximum length mm., maximum width mm., maximum height mm. Cephalon and protopy- gidium subequal in size. Occipital ring of width (tr.) about one-third total width, defined posteriorly by shallow ring furrow, anteriorly by extremely faint occipital furrow, and set off from pleural region by its convexity. Axial furrow in front of occipital ring is indicated by change in slope between gently convex gla- bella and cheek; axial furrows diverge slightly forwards and run in a straight course to margin. Glabella extends to anterior. Figure 4. Benwpleurides caclatus A, B, C, protaspis, laclcing free cheeks aud hypostome, anterior, posterior, and left lateral views, X 26 (compare PI. 2, figs. 2, 4). Abbreviations: o, anterior cephalic spine; ah, anterior branch of suture; fx, fixigenal spine; or, occipital ring; p, i^ostero- lateral spine on protopygidium; pb, posterior branch of suture; pi, palpeliral lobe; /, tubercle. edge of shield, which is bent down. Pair of tinj^ tubercles on anterior slope. Fixed cheek gently convex and outward-sloping, palpebral lobe not raised or defined other than by long, curved sutural margin; anterior branch of suture runs from palpebral lobe forward and outAvard, then curves inward to margin; pos- terior branch runs in " S" curve and is directed more strongly outward. At anterolateral corner of fixed cheek there is a thick spine directed forward and slightly outward; at posterolateral corner there is a spine of similar size, the fixigenal, directed backward and more strongly outward. There is only the faintest trace of a transverse furrow, directed outward and slightly back, separating fixed cheek from ]-)leural region of protopygidium,
Size: 2904px × 861px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorharvarduniversity, bookcentury1900, booksubjectzoology
