320 



first volume of their ' Manual of Palaeontology,' published in 1889, follow 

 Johannes Muller's classification of the Cystoidse, and divide the class 

 ' into the three orders, of the Aporitidse, Diplopo ritidse and Rhombiferi, 

 according as the calycine plates are imperforate, are pierced by yoked 

 pairs of pores indiscriminately distributed, or have their pores arranged 

 in pore-rhombs.' Of these three orders, Astrocystites would seem to be 

 most probably referable to the Diploporitidie." Figures 21-, 21a & 22 

 of this paper are reproductions of original drawings by Mr. L. M. Lambe. 



A few months later, in a postscript to this paper, published in the Can- 

 adian Record of Science for July, 1897, but which was not issued until 

 January, 1898, the generic name Astrocystites was changed to Stegano- 

 blastus, at the suggestion of Dr. F. A. Bather, who thought that it was 

 too near to Asterocystis, Haeckel (1896). 



The specimens upon which S. Ottawaensis were based have since been 

 studied somewhat exhaustively by Dr. Bather, whose general conclusions 

 thereon are summarized in part III, chapter XII, of the " Treatise on 

 Zoology," edited by Dr. E- Ray Lankaster, and published in 1900. Dr. 

 Bather thinks that Steganohlastus is more nearly related to Edrioaster 

 than to Asterohlastus, and makes it the type of a new family, which he 

 calls Steganoblastidae, and places in the class Edrioasteroidea of E. Bill- 

 ings. The family and genus are thus described, and the typical species 

 figured (but with other numbers) by Dr. Bather, on pages 209 & 210 of 

 the volume cited. 



"Family 4. Steganoblastid/e. Edriasteroidea, with a rigid theca 

 composed of plates relatively larger and thicker than in other families 

 of this class ; these include elements comparable to the R R and B B 

 of Blastoidea ; B B attached to a stem, probably short ; ambulacra des- 

 cend into the radials. Genus — Steganohlastus, Whiteaves (1897, origi- 

 nally described as Astrocystites, name preoccupied), Ordovician, Canada " 

 (figs. 23 and 24). " The remarkable resemblance to Asterohlastus, in- 

 sisted on by its founder, suggested the reference of Steganohlastus to the 

 Protoblastoidea (Bather, 1899); but the ambulacra are now known to 

 have essentially the same structure as in Edrioaster, while the absence of 

 brachioles may be maintained with confidence. Theca piriform, its plates 

 strongly marked with axial folds, and consisting of : B B (5 ?, sutures not 

 clear) ; R R, 5, alternating with B B, and receiving the distal ends of the 

 ambulacra ; interambulacrals, one large one and an uncertain number of 

 smaller ones, in each interradius ; 5 slightly pitted plates of spear-head 

 .shape, stretching up between the ambulacra to the oral pole and simula- 

 ting O of Crinoidea or l\ of Blastoidea, but perhaps being only proximal 

 covering-plates. The anus pierces one interambulacrum, and slightly 

 disturbs the pentamerous symmetry of the theca. From the mouth 5 am- 

 bulacra stretch about half-way down the theca ; the adambulacrals (side- 



