278 Prof. F. M'Coy on some new genera 



numerous; inner area rather more than half the diameter, 

 forming a circular mass of confused vesicular tissue crossed 

 by a few arched radiating delicate lamellae : vertical section 

 having the narrow outer area on each side (corresponding to 

 the lamelliferous zone) of arched vesicular plates^ forming large 

 unequal horizontal or slightly mclined cells, one or two ex- 

 tending across the width of the area ; wide inner area com- 

 posed of small oval cells arranged in much-curved transverse 

 rows, the convexity of the curve upwards. 



Wenlock limestone, Wenlock. 



Arachnophyllum typus (M'Coy). 



Syn. & Ref. Acervularia Baltica (Schw.), Lonsd. pars S. S. 1. 16. 

 f . 8 « (not of Schweigger). 



Sp. Char. Corallum forming thick, irregular, enveloping masses ; 

 upper surface undulated, covered with large shallow polygonal 

 stars, defined by very obtusely angular ridges ; the centres 

 averaging 7 or 8 lines apart, circular, depressed, rather more 

 than one-third the diameter of the star, radiated with about 

 thirty-eight strong granulose subalternate lamellse, half of 

 which reach the flattened centre, where they are irregularly 

 united and slightly twisted ; on the outer inclined area of each 

 star, each of the lamellse becomes much thinner and more 

 faintly marked, branching di- or tri-chotomously once or twice, 

 and often waving in a variable manner before reaching the 

 boundary, over which they frequently pass into the adjoining 

 stars : vertical section showing a few delicate vertical striae 

 under the centres of the stars (edges of the twisted vertical 

 lamellse), and a nearly uniform small vesicular tissue, the cells 

 of irregularly unequal size, passing from star to star, with a 

 few irregular dense bands nearly coinciding in curvature with 

 the form of the cells ; avei'age of larger cells two to three in 

 1 line ; no divisional walls between the stars. 



That this is one of the fossils figured by Mr. Lonsdale in the 

 ' Silurian System ' as the Acervularia Baltica of Schweigger I 

 have little doubt, but neither the particular figure to which I re- 

 fer, nor the others which that writer has given under the same 

 name in that work, have any specific relation to the Acervularia 

 Baltica of Schweigger, who avows that name to be only a syno- 

 nym of the A. ananas (Linn, sp.), referring to the original figure, 

 &c. in the ' Amoenitates Academicse ' of Linnaeus, representing a 

 coral which has a distinct walled tubular centre, from which the 

 groups of young are developed, solid walls between the cells, &c. 

 The lateral disk buds are often seen in this curious coral. 



Wenlock hmestone near Aymestry . 



