Page:Quarterly Journal of the Geological Society of London, vol. 33.djvu/76

46

, sp. nov. Plate III. figs. 3–5.

The test is small, depressed, rather pentagonal in outline, and the ambitus is rounded. The actinal surface is slightly rounded from the ambitus to the mouth, but on the whole is flat. The interambulacra are twice the width of the ambulacra at the ambitus, and about one third broader at the actinosome. The pores are in a vertical row and slightly oblique, and their zones are sunken. The interambulacra have two rows of primary tubercles, which are small and imperforate. Each row is separated externally by a crowd of closely placed secondaries from the poriferous zone, and by a much wider space from the other row. This space is marked by ridges which radiate from the top and base of the primaries, and which have secondary tubercles upon them and between them. The ridges run parallel courses between the distant primaries, and are narrow, but support from four to six secondaries. There are short ridges between the primary tubercles in each vertical series, which also carry one or more secondaries. Transverse and elongated spaces exist on one side of the primary tubercles at the ambitus and elsewhere where this ornamentation is not seen. The primaries of the ambulacra are in two vertical rows, each being close to its poriferous zone. Their ornamentation by ridges and secondaries is the same as that of the interambulacra; but the ridges which pass off towards the poriferous zone, cross it and separate the pores in vertical series. All this ornamentation is exsert and the plain surface of the test may be seen between the ridges. Around the base of the boss of the large tubercles the ridges often close in and produce a crenulated appearance.

Height of test inch, breadth  inch.

Locality.—Mordialloc, No. 1.

In classifying this species in the genus Temnechinus, I have been led by A. Agassiz, in his admirable criticism on this group of the Temnopleuridæ (op. cit. p. 286). He mentions that D'Archiac and Haime have figured from the Nummulitic formation of India a number of species which are usually referred either to Temnopleurus or to Opechinus, but which belong to this same genus Temnechinus. Probably Paradoxechinus novus, Laube, is one of these, and has had its ornamentation irregularly distributed.

, Gray.

A large Echinoderm from the Mitchell-River Tertiaries, in Eastern Victoria, so closely resembles the modern form from Brisbane, Japan, the Sandwich Islands, and California, which has been termed