. Annual report. New York State Museum; Science; Science. 360 354 thecae of the mature part of the rhabdosome is very characteristic, their distal free parts standing out as series of squares from the broad median part of the lateral face. This squarish aspect of the thecae is, besides their straight apertures and straight outer margins especially due to their equally straight outer walls opposite the apertures of the preceding thecae. This geniculated part of the thecal wall is so much thicker than the others that it clearly stands out above the latter and in some specimens it is even produce
. Annual report. New York State Museum; Science; Science. 360 354 thecae of the mature part of the rhabdosome is very characteristic, their distal free parts standing out as series of squares from the broad median part of the lateral face. This squarish aspect of the thecae is, besides their straight apertures and straight outer margins especially due to their equally straight outer walls opposite the apertures of the preceding thecae. This geniculated part of the thecal wall is so much thicker than the others that it clearly stands out above the latter and in some specimens it is even produced into a mucro [see text fig. 354]. In all other congeners this f part of the thecal wall is very dis- tinctly concave or depressed. From C . b i c o r n i s, with which it may be found associated, it differs, aside from the absence of the lateral spines, in the narrower sicular ex- tremity, the more rapid and less uni- form widening' of the rhabdosome and the wider apertural excavations. The only species of Climacograptus in the graptolite shales of New York that possesses a similarly slender 1 • • /~» 1 Fig- 359-61 Mature portion and sicular extremities of speci- SlCUlar extremity IS L. CaUClatUS. mens from lower third of Eden shale at Covington, Ky. (Ulrich coll.). Fig. 362 Portion of variety from Lees Gulf, Lewis CO., This goes still beyond C. typi- N,Y- x5 c al i s in the slenderness of its rhabdosome and attains its maximal width much slower. C. parvus has squarish thecae like C. typical is, but it can for this reason not yet be considered as a dwarfed mutation of C . t y p i c a 1 i s, as Freeh has done [1897, ] ; for it precedes the latter and is separated from its horizon by the zone of Diplograptus amplexicaulis in which it is absent, and it has a greatly different rhabdosomal Fig. 354-62 Climacograptus t y p i c al i s Hall. Fig. 354 Copy of one of Hall's original figures, representing a longitudi- nal section. Fig. 355 Gurley's ms drawing. x 2. F
Size: 798px × 3133px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectscience, bookyear1902
