FOLKE TOLKESON, MADREPORARIA. 



Localities: 1. 48 miles W.S.W., 15.7.11, 78 feet; 2. 45 milos W.S.W., 17.7.11, 72 

 feet; 3. 48 miles W.S.W., 15.7.11, 78 feet; 4. 45 miles W.S.W., 17.7.11, 72 feet; 5. 42 

 miles W.S.W., 11.7.11, 36 feet. 



o. 



Long dia- 

 meter of 

 caliee in mm 



Short d 

 meter 

 caliee in 



ia- 



of 



mm 



Height 

 in mm 



Scar in mm 



1 



15 



6,4 





13,5 



7,4X2,5 



2 



14,8 



6,9 





10,3 



7,0X2,7 



3 



14,1 



0,6 





10,8 



6,9X3,5 



4 



14 



B 





9,6 



7,7X3,2 



5 



13,5 



7,3 





13,8 



3X2,5 



Nos. 1 and 4 have each 96 septa (nos. 2 and 3 are preserved with the polyps in 

 spirit, whence their septa cannot be counted) and correspond in other respects also to 

 the description and figure by Edwards & Haime. 



No. 5 differs somewhat in general appearance: the caliee is more open, and the 

 exteriör form of the corallum reminds one of the specimen reproduced by Semper in his 

 figure 13, plate XVIII. Still the pedicel is lacking; the basal scar is verv small. The 

 flattened base, of which Semper speaks, is very well developed, and on each edge it is 

 provided with one (broken) process like many specimens of the genus Flabellum. This 

 base (Semper's Amme) has at its upper part an annular groove still more pronounced 

 than the specimen described by this a ut hor. 



No. 5. has 64 septa only; the septa of the two first cycles and some septa of the 

 third cyele are developed to the same extent and reach the columella, which is not so 

 regular as those in the specimens mentioned above. 



Genus Heterocyathus. 



Edwards & Haime established in 1851 (Monographie des polypiers fossiles des 

 terrains palaeozoiques, p. 127) two genera, Stephanoseris and Psammoseris, which, as to 

 their general appearance, resembled Heterocyathus very strikingly. The systematic po- 

 sitions of these three genera and their mutual relations have been repeatedly discussed. 



Stephanoseris. As regards this genusj the type-species, S. rousseaui (E. & H. ), 

 has generally been considered to be a Heterocyathus by authors låter than Edwards & 

 Haime. Tenison-Woods (1877, 27, p. 297), Moseley (1880, 24, p. 145), Marenzel- 

 ler (1888, 22, p. 17), Vaughan (1905, 29, p. 416), Botjrne (1905, 4, p. 193), Poole 

 (1909, 18, p. 898), and Harrison (1911, 17, p. 1026) are all of that opinion. 



In his researches (1904, 12, p. 104-112) on the variation of Heterocyathus aequi- 

 costatus E. & H. Gardiner does not enter into any discussion of this question, but in 

 his work of 1905 (14, p. 933-934) he unites the two genera Psammoseris and Stephano- 

 seris under the cominon name of Psammoseris, and bases this unification on the fol- 

 lowing grounds: >>I unite these two genera, since my series of specimens show inter- 

 mediate forms in all the characters which are supposed to separate them. » Further 

 he says: »It {Psammoseris, syn. Psammoseris and Stephanoseris E. & H.) represents 

 either a case of parallel evolution in the Fungidae to the Turbinolidae, or is an inde- 



