182 BRITISH STROMATOPOROIDS. 



6. Stromatopora florigera, n. sp. PL XXII, figs. 8 — 10. 



The form, size, and mode of growth of the coenosteum in this species are 

 unknown. The coenosteal tissue is not developed in latilaminae, and is completely 

 reticulated (Plate XXII, fig. 9), the skeleton-fibre being coarsely porous in struc- 

 ture, and having an average diameter of from j to ^ mm. The astrorhizae are 

 exceedingly numerous and are of small size, their centres being in general about 

 4 mm. apart (Plate XXII, fig. 8). The astrorhizae are developed in vertically 

 superimposed rows, each system being traversed by an axial wall-less canal ; but 

 proper " astrorhizal cylinders " are not usually developed. From the condition of 

 the astrorhizae it may be inferred that the surface exhibited close-set conical 

 " mamelons " corresponding with the centres of the astrorhizal systems. Tan- 

 gential sections (Plate XXII, fig. 9) show the completely reticulate character of 

 the general skeleton, into which the minute astrorhizae melt insensibly at their 

 edges. Vertical sections (Plate XXII, fig. 10) show that the radial pillars are 

 clearly recognisable, and that well-developed zooidal tubes, traversed by numerous 

 transverse partitions or " tabulae " are present. Such sections also commonly 

 exhibit the axial canals of the astrorhizal systems. About six zooidal tubes, with 

 their intervening pillars, occupy a space of 2 mm. measured transversely. 



Obs. — This species is of the same general type as S. ffiipschii, Barg., from 

 which it is chiefly distinguished by the more delicate character of the skeleton- 

 fibre, the much smaller size and greater proportionate number of the astrorhizae, 

 and the fact that these structures are developed in regular vertical systems. 

 From 8. Hupsehii, var. seposita, Nich., in which the astrorhizae are also developed 

 in vertical systems, 8. florigera is separated by its more delicate texture, the much 

 more closely-set astrorhizae, and the fact that astrorhizal cylinders are usually 

 wanting. The zooidal tubes of 8. florigera are also furnished with more numerous 

 tabulae than is the case with those of 8. Hupsehii, Barg. There is no other species 

 of the genus Stromatopora with which the present form could well be confounded. 

 My material of 8. florigera is, unfortunately, very limited, and I am unable to 

 give any information as to the general form of the coenosteum or the condition of 

 its surface. I have seen no specimens in the " Caunopora-state," but examples 

 occasionally occur in the "reversed " condition. 



Distribution. — This species is only kiiown to me as occurring rarely in the 

 pebbles of Devonian Limestone in the Triassic conglomerates of Teignmouth. 



