. Bulletin - New York State Museum. Science. IJEEKMANTOWN AND CHAZY FORMATIONS OF CHAMTLAIN BASIN 4O3 The conch, if not circular in section, may be either compressed (when the transverse diameter has been shortened) or depressed (when the dorsoventral diameter lias been shortened). The direction of the conch is designated as apicad (in apical direction), orad (in oral direction), dorsad and ventrad. The apertural margin frequently possesses, besides the hyponomic sinus, lateral expansions, termed crests or lappets. The sipliuncle is the calcareous tube containing the fleshy siphon. It may be t
. Bulletin - New York State Museum. Science. IJEEKMANTOWN AND CHAZY FORMATIONS OF CHAMTLAIN BASIN 4O3 The conch, if not circular in section, may be either compressed (when the transverse diameter has been shortened) or depressed (when the dorsoventral diameter lias been shortened). The direction of the conch is designated as apicad (in apical direction), orad (in oral direction), dorsad and ventrad. The apertural margin frequently possesses, besides the hyponomic sinus, lateral expansions, termed crests or lappets. The sipliuncle is the calcareous tube containing the fleshy siphon. It may be tubular or nnininuloidal (moniliform) ; i. e. inflated in the interseptal spaces. The. Subventran Propioventran ExtrAc entroventrAn Centroventran Intracentroventrdin Ventrocsntren Centren Dorsocentren Int racent rod or san Centrodorsan Extracentrodorsan Propiodorsan Subdorsan position of the siphuncle with- in the phragmocone can be precisely stated by the use of the terms given in the ap- pended diagram [text fig. i]. The cctosiphuuclc is the ex- ternal wall of the siphuncle; the endosiphuncle comprises all structures within the same. The anterior or upper part of large siphuncles remains un- obstructed and was doubtless occupied by an extension of the mantle cavity. This part of the siphuncle is here term- ed endosiphocylinder (Hyatt's endoconal or siphuncular chamber). It is followed apicad by the endosipliocone, a conical extension of the same cavity, bounded by the endosiphosheath (Hyatt's endocone). The endosiphocone is continued in forms with organic deposits in a tube to the apex; this tube is the endosiphotuhe (endosiphuncle Hyatt, prosiphon Zittel). Sometimes a wider broad flat tube, clos- ing apicad into a double plate, extends apicad from the endosipho- cone. This is the endosiplwcoleon. The endosiphotuhe and endosi- phocoleon may be suspended by membranes (endosiplioblades). The siphuncular wall or ectosiphuncle consists originally entirely of the septal necks or fu
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectscience, bookyear1887
