less developed than the others; and those of the inner or posterior zones of the lateral posterior ambulacra are few in number towards the ambitus, to which, however, they extend. The ocular pores are well developed, and a miliary granulation covers the test between all the pores and the interporiferous areas, a few scattered tertiary tubercles being there also. The tuberculation is small, and tubercles of the third order are the largest on the upper surface. They increase in number towards the ambitus, and are surrounded by a sunken scrobicule surrounded by miliaries. The keel is distinct, slightly angular, and reaches backwards so as nearly to overhang the ambitus.
The concave actinal surface has a large sunken mouth, a plain band reaching from it posteriorly, and a distinct tuberculation at the edge of the test.
Length of specimen 1910 inch, breadth 1810, height 610.
Locality.—No. 5 Upper Coralline Beds, Castle Cove, near Cape Otway.
The resemblance of this species to Rhynchopygus pacificus, Ag. (Rev. Ech. Part i. p. 153 and Part iii. p. 554), is very decided in some points; but it differs from it and from the species from the Caribbean Sea by having an elongated apical system, and in the separated apical ends of the lateral and posterior pairs of ambulacra. This Dysasterian peculiarity resembles that of Hyboclypus, which may be said to be a Galerites with an elongated apical system, thus uniting this last genus to Ananchytes. The Australian Lower Cainozoic Rhynchopygus is unlike all the other species of the genus in this special peculiarity. The genus is represented in the Gault, in the uppermost Cretaceous rocks, and in the Tertiary tuff of Guadeloupe; and the recent forms are from the Caribbean and the Pacific coast of America. Were it not for the strong generic resemblance of the new species, the nature of the curious and suggestive apical system might determine the formation of a new genus; but it is perhaps most advisable to retain the form where it is placed, so as to make it a passage species from one great group to another.
Genus Echinobrissus, Breyn, 1732.
Nucleolites, Lamk. (part.)
Echinobrissus australiæ, sp. nov. Plate III. fig. 11.
The test is depressed and stout, and the outline of the ambitus is elliptical. Seen from above the posterior end is slightly produced, and the anterior is rounded. The vertex is central, and the apical system is anterior to it. The petals are lanceolate and narrow; the anterior extend rather more than halfway down the test; the posterior are about the same length; and all are open. The poriferous zones are of uniform breadth; and the interporiferous space is nearly of the breadth of one of the zones: it is very slightly raised so as to prevent the ambulacra being flush with the test. The pores are subequal; those of the inner row are round, whilst those of the
