Hydractinia, Parkeria, and Stromatopora. 75 



Fig. 10. The same. Longitudinal section of a tube magnified, showing 

 the " aunulation ;" a, tranverse section to show the diaphrag- 

 matic form of the constriction, with hole in the centre. 



Fig.W. Hydractinia Vicaryi, n. s^. (fossil), nat, size. Portion of natural 

 surface, showing : — a, large spines ; b, circular area, to which the 

 apertures of the surface are added j all the rest having been 

 omitted for perspicuity. 



Fig. 12. The same. Cast of tube, showing annulations. a, cylindrical 

 form of the cavity in which the cast {h) is found. 



Fig. 13. Parkeria sphcerica. Vertical section, natural size, a, infil- 

 trated or consolidated zone or shell ; 6, semi-infiltrated zone ; c, 

 w^infiltrated portion, or kernel ; d^ the first six laminse of c, 

 delineated to show intervals traversed vertically by the radiating 

 tubes ; the innermost elliptical, at one end of which the dark 

 portion represents a cavity in which probably there was some 

 kind of foreign body. 



Fig. 14.' The same. Diagram of tissue-fibre, magnified to show its re- 

 ticulated, anastomosing, contorted arrangement and its composi- 

 tion, fl, fibre, composed of colourless transparent calcspar ; h, 

 coating or incrustation, composed of granular, crystalline, yellow- 

 ish calcite. 



Fig. 15. The same. Diagram of portion of surface of kernel (fig. 13, c), 

 showing : — «, ends of radiating pillars of tissue-fibre ; 6, circular 

 area, to which the ends of the radiating tubes are added. Natu- 

 ral size. 



Fig. 10. The same. Diagram of portion of natural sm'face of a specimen 

 \\ inch in diameter, showing : — a, ends of radiating pillars of 

 tissue-fibre ; h, circular area, to which the ends of the radiating 

 tubes are added. Natural size. 



Fig. 17. The same. Vertical section, natural size, a, circle indicating 

 size of specimen; 6, the first six laminse, delineated to show 

 intervals traversed vertically by the radiating tubes ; c, foreign 

 nucleus, consisting of a fragment of a Nautiloid test. 



"^ig. 18. Loftusia 2)€rsica, Brady. Portion of natural surface, natural 

 size, a, papilliform apertural eminences of radial tubes; 5, 

 boss-like eminence, presenting, c, a trace of branched lines across 

 (? radiatiug) from the summit. 



Fig. 19. Stromatopora with bossed surface, in black-grey Devonian 

 limestone. In the possession of Mr. Vicary. Portion of natm'al 

 surface, natural size, a a a, bosses presenting the " stellate 

 system of canals " respectively on the summit ; b, papUlary aper- 

 tures of radial tubes. 



Fig. 20. Stromatopora in grey Devonian limestone, subinfiltrated. In the 

 possession of Mr. Vicary. Diagram of horizontal section, na- 

 tural size, a, stellate systems of canals ; b, ends of radiating 

 tubes. 



Fig. 21. The same. Horizontal section of ends of radiating tubes, magni- 

 fied, to show intertubular communication like that of Syringo- 

 pora : a, longitudinal section of tube, to show diaphragmatic 

 lines and appearance of annulation ; b, intertubular communi- 

 cations. 



Fig. 22. Stromatopora (Syringo2}07'a'), in grey Devonian limestone. In the 

 possession of Mr. Vicary. Nearly horizontal section, natural 

 size, a, stellate system of canals ; b, ends of the radiating tubes, 

 much larger than in the foregoing instance. 



Fig. 23. The same. Section of radiating tube, magnified, to show the dia- 

 phragmatic lines of annulation cut obliquely. 



