286 ON SOME NEW AUSTRALIAN ECHINI, 



larger and more conspicuous, and the whole test smaller and 

 more angular, almost pointed at the greatest diameter. There 

 are of course many other minor differences, but the two species 

 cannot possibly be mistaken for one another. 



PhYLL ACANTHUS PARVISPINA, n. S. 



Test elevated, solid, flattened at each end, but not swollen at 

 the sides. Poriferous zone, slightly undulating, rather broad ; 

 ambulacral area with a regular row of miliaries bordering each 

 side, and two or three rows of smaller and less prominent ones 

 in the central area. Primary tubercles, eight, but the two last 

 near the actinosome small and crowded. Mammary boss elevated, 

 with a large perforation, and with a rather deep groove round 

 the neck so as to give a hemispherical surface to the boss, which 

 is raised on a smooth conical mound. Scrobicular area, somewhat 

 squarely oval, margined by an irregular row of secondaries, and 

 then surrounded by a thickly packed mass of miliaries, which 

 decrease in size to the coronal sutures which are well and 

 distinctly marked, but not deeply, and the whole aspect of the 

 interambulacral space is solid and elevated. Actinosome large, 

 round, with the series of plates covered with short flat spines on 

 secondary tubercles. Auricles remarkably broad, stout, concave, 

 united below for some distance, but the arch not complete, leaving 

 a broad wedge-shaped opening. Anal system large. Genital 

 plates nearly square with the opening, small and exactly in the 

 centre. Madrepoin body twice the size of the others, with the 

 pore a third of the width from the edge. Ocular plates quite 

 excluded, crescentic in shape. Anal plates rather large on the 

 outer side, but numerous and gradually decreasing towards the 

 opening, which is also large. The whole system densely covered 

 with miliaries, which are rather larger at the edges of the plates. 

 Primary spines rather short, slender, tapering very slightly, 

 obliquely bevilled at the extremity, where they are very 

 conspicuously grooved for a short distance. The rest of the 



