tlie G^'ewMS Fistulipora, M^Coy. 511 



may be contained within the space of 1 millim. The folds 

 occupy from one fourth to one fifth of the circumference of the 

 autopores. - 



Ohs. The relationship between Fistidipora utriculus and 

 this species has already been pointed out. 



We are indebted to Dr. Henry Woodward, F.R.S., for his 

 kindness in permitting us the use of specimens contained in 

 the collections of the British Museum (jSTat. Hist.) in pre- 

 paring the foregoing description. 



Fistulipora dohunica *, Nich. & Foord. 

 (PI. XVII. figs. 3, 3 a, 3 h.) 



Corallum extremely thin, incrusting ; attaching itself to 

 various foreign bodies, whose surface contour it follows in all 

 its irregularities ; occasionally, however, putting forth short 

 hollow cylindrical prolongations, generally at right angles to 

 the surface (fig. 3). Surface dotted with maculge. The 

 corallites, though very minute, can usually be seen by the 

 naked eye. About six of the autopores are contained within 

 the space of 1 millim. ; others, of a little larger size, occur in 

 the vicinity of the macula. The folds in the autopores are 

 well developed and occupy nearly one tliird of the circum- 

 ference of the walls of those corallites (fig. 3 a). There is 

 nothing remarkable in the microscopic structure as seen in 

 longitudinal sections. 



Obs. As might be supposed, some difficulty was experi- 

 enced in obtaining satisfactory sections from such an extremely 

 thin corallum. 



Some of the autopores have been shaded, the better to 

 distinguish them from the mesopores. 



We are unacquainted with any species with which to com- 

 pare F. dohunica. The extreme tenuity of its corallum and 

 its incrusting habit resulting from this, together with the 

 minuteness of its corallites, are the distinguishing marks of 

 this species. The specimen figured is from the collection of 

 ]\ir. Madeley, of Dudley. 



Formation and Locality. F. dohunica appears to be tolerably 

 plentiful in the Wenlock Shales (Upper Silurian) at Dudley. 



Fistulijpora eriensis, Rominger. (PL XVII. figs. 4, 4 a.) 



Fistulipora eriensis, Rominger, Proc. Acad. Nat. Sci. Phil. p. 121 

 (1866). 



Corallum in large, irregular, laminated and folded masses ; 



* The Dobunii were a tribe of ancient Britons, neighbours of the 

 Silures. 



