. The Cambridge natural history. Zoology. HEXACTINELLIDA 201 arrangement of the spicules is best realised by means of a diagram (Fig. 93). The deviations from this ground-plan of Hexactinellid struc- Prostalia / Prinoipalia -------<IV--,.]x Comitalia--/-â : â¢;-'l\ Intarmedia m ^'^ Dermalia Canalaria---â¢â â â â -if ...';;- 1",^ { " Hypoderm - -%. Dictyonalia Prostalia basalla Fig. 93.âScheme to show the arrangement of spicules in the Hexactinellid skeleton. Oanalaria, microscleres in the walls of the excurrent canals ; Dermalia Auto- dermlalia'], microsclere
. The Cambridge natural history. Zoology. HEXACTINELLIDA 201 arrangement of the spicules is best realised by means of a diagram (Fig. 93). The deviations from this ground-plan of Hexactinellid struc- Prostalia / Prinoipalia -------<IV--,.]x Comitalia--/-â : â¢;-'l\ Intarmedia m ^'^ Dermalia Canalaria---â¢â â â â -if ...';;- 1",^ { " Hypoderm - -%. Dictyonalia Prostalia basalla Fig. 93.âScheme to show the arrangement of spicules in the Hexactinellid skeleton. Oanalaria, microscleres in the walls of the excurrent canals ; Dermalia Auto- dermlalia'], microscleres in the dermal membrane ; D. Hypodermlalia], moi-e deeply situated dermalia ; Dictyonalia, parenchymalia which become fused to form the skeletal framework of Dictyoniua ; Gastralia Autogastr^aKa], microscleres in tlie gastral membrane ; Gastralia Hypogastr\alia'], more deeply situated gastralia ; ParencJyyinalia Principalia, main supporting spicules between the chambers ; P. Comitalia, slender diaotine or triactiue spicules accompanying the last; P. Intermedia, microscleres between the P. principalia ; Prostalia, projecting spicules ; P. iasalia, rooting spicules, from the base ; P. marginalia, defensive spicules, round the oscular rim ; P. pleuralia, defensive spicules, from the sides. (Prom Delage and Herouard, after F. E. Schulze.) ture are few and simple. They are due to folding of the chamber- layer, or to variations in the shape of the chambers, and to increasing fusion of the spicules to form rigid skeletons. A simple condition of the chamber-layer, like that of the young sponge of Fig. 89,. 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 Harmer, S. F. (Sidney Frederic), Sir, 1862- ed; Shipley, A. E. (Arthur Everett), Sir, 1861-1927. ed. [London, Macmillan and Co. , Limited; New York, The M
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
