8 FOLKE FOLKESON, MADREPORARIA. 



t lie young state 011 a gastropod shell, which it subsequently envelops, and in the adult 

 the shell, and the spiral basal cavity continuous with it, is tenanted by a Sipunculid 

 of the genus Aspidosiphon. » 



Heterocyathus has always been considered a Turbinolid coral; Stephanoseris and 

 Psammoseris have been referred now to the Fungiidae, now to the Turbinolidae, and 

 occasionally to the Eupsammiidae. The characteristics on the ground of which the three 

 genera have been established, are the presence or absence of pali and synapticula; but 

 these factors are very variable and by no means justify the retention of all three 

 genera. To ni}' mind, all the specimens in question are very elosely relä t ed and must 

 belong to the same genus, viz. Heterocyathus. 



Heterocyathus aequicostatus Edwards & Haime 1848. (Figs. 4—9). 



Heterocyathus aequicostatus Edwards & Haime 1848 (10), p. 324, plate X, fig. 8. 



Stephanoseris rousseaui (Edwards & Haime 1848), (10), p. 324, plate X. figs. 9, 9 a; Edwards 1860 



(8), III, p. 57. 



Heterocyathus phiUppinensis Semper 1872 (20), p. 254, plate XX, figs. 12— U. 



Heterocyathus parasiticus Semper 1872 (20), p. 255, plate XX, figs. 17 a — c. 



Heterocyathus pulchellus Rehberg 1893 (25), p. 8, plate I, figs. 7 a, 7 b. 



Heterocyathus ohlongatus Rehberg 1803 (25), p. 9, plate II. figs. 1, 2. 



Heterocyathus wood-masoni Alcock 1893 (1), p. 141, plate V, 4, 4 a. 



Heterocyathus aequicostatus Gardiner 1904 (12), p. 105, plate III, figs. 1 — 43. 



Gardiner (12, p. 105) describes two types of this species, to which he refers the 

 above-mentioned species except S. rousseaui (E. &H. ) and H. wood-masoni Alcook, and 

 considers them to be »two perfectly distinct modes of growth ». 



Miss Harrison (1911, 17, p. 1026), in examining this genus, has restricted it to three 

 species: H. aequicostatus E. & H., which includes all the above-mentioned species and 

 is identical with Gardiner's Type I; II. alternatus Verrill (= Gardiner' s Type II); 

 //. heter ocostatus established by miss Harrison. 



As regards H. alternatus, I consider it a good species, which is well separated from 

 Gardiner's Type II. As to Gardiner's two types, I am inclined to agree with Gardi- 

 ner himself, and I consider them to be only varieties of the same species. As to //. 

 heterocostatus Harrison, 1 am unable to express anv opinion. 



Dr. Mjöberg's specimens of H. aequicostatus form natural groups, each with its 

 spccific characters. I refer them all to H. aequicostatus, however, in view of the great 

 variability of this species, to which Gardiner first called attention. 



Total no. of 

 No. Locality specimens 



a 1 42 miles W.S.W. off Cape Jaubert, 11.7.11, 36 feefc '2 



b » 9.7.11, 60 » 3 



c 45 » , 2.7.11, 70 » 



1 figs. 4 — 5. 



As to the costae, the base and the theca these specimens agree perfectly with Gar- 

 diner^ Type I. Septa 48: those of different cycles are remarkably unequal. The 

 primaries are by far the highest, and in several places even higher than the base. The 

 edges of the smaller septa are toothed close by the columella, at which paliform teeth 



