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ON A YOUNG SPECIMEN OF A TEMNOPLEURUS.
BY THE REV. J. E. TENISON-WOODS, F.G.S., F.L.S.
[Plate XV., figs. 3, 4, and 5.]
The species here described was dredged up from a few fathoms at Port Denison. It appears to me to belong to the genus Temnopleurus, and as far as I can judge belongs to a new species. It is principally distinguished by the extent and depth of the pits on the coronal plates. Unfortunately there are no perfect specimens and the anal system is entirely wanting. There are two single rows of large tubercles (primary) in each area, and secondaries are scattered in irregular double lines on the ridges between the sutural pits. On the ambulacral area this line is close to the pores, which are a single row of double pores. On the interambulacral area there is a very irregular line of secondaries between the line of pores and the row of primaries. The tubercles have a conspicuous smooth base and a rather large area which is also smooth. The sutural pits are regularly oval, and equally deep. The shape of the test is circular and depressed not conical. The actinosome is large, round, without cuts and the arches are broad, rather high, solid, united above and connected with one another by hood processes.
Prof. A. Agassiz has given us such full information about the young stages of Temnopleurus that we aro able to pronounce once upon any small urchins belonging to the genus. The specimen in question does not belong to T. Hardwickii, as in that species the sutural pits are altogether wanting on the actinal
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surface, while here they are as conspicuous as on any part of the test. Temnopleurus Reynaudi has a conical outline and the pits are different. In T. tornematicus, the secondary tubercles form oblique lines and the portion of the ambulacral plates which lies between the sutural cavities has a band-like character.
From all these circumstances I regard the urchin here figured as new, I do not think we are dealing with a very young stage, but as I cannot give any information or surmise about the adult state, I name the species only provisionally and distinguish it as Temnopleurus cavernosa.
