FROM THE AUSTRALIAN TERTIARIES. 



423 



The length of these petals is 31 millim., width in the middle 

 6 millim., extreme depth of the depression 6 millim. There are 

 forty pairs of pores, and the interporiferous area is very eqnal in 

 width throughout, except near the radial plate, and is slightly 

 narrower than the poriferous zone. The an tero -lateral petals are 

 longer than the others (33 millim.), their width is 6*5 millim., 

 and they are shallower, 4 millim. The highest part of the test is 

 in interradia 1 and 4, and near the apex, which is excentric in 

 front. The slope is sudden from the apex in front, and gradual 

 behind for a short distance, and then there is some tumidity of the 

 posterior interradium. There is no keel there, and the interradium 

 is rather narrow on account of the angle made by the ambulacra 

 being 60 degrees. 



The anterior petals diverge at an angle of 120 degrees. The 

 posterior truncation is low and broad, and the periproct is close to 

 the upper edge of it and is elliptical transversely. Width of the 

 truncation 60 millim., height 35 millim ; height of the periproct 

 11*5 millim., width 21 millim. There is a slight re-entering 

 curve quite at the posterior actinal edge. The actinal surface is 

 very flat, and the large, wide, very anteriorly placed mouth has a 

 downward projecting labium 22 millim. broad. 



The ornamentation is largest on the flanks of the anterior groove, 

 and consists of small perforate mamelons on conical bosses, crenu- 

 lated and placed on a level, large, plain scrobicule, with miliary 

 granules on the edges. Elsewhere the tubercles are smaller, and 

 there is a small granulation between their more distant scrobicules. 



Locality, Murray Cliffs. This specimen is slightly larger than 

 that which was figured in the former communication and which, 

 unfortunately, has been mislaid. 



21. Pericosmus gigas, M'Coy, Prodr. Pal. Vict. dec. vii. 1882, pis. 64 

 & 65, p. 15. 



This huge species attains the length of 7 inches 6 lines and is 

 nearly as broad, the height, however, being only about one half of 

 the length. The specimens described by M'Coy are wonderful, and 

 the minute ornamentation, the peripetalous fasciole clinging to the 

 petals and reaching along the anterior one to behind the deep notch, 

 and the lateral fasciole are very characteristic of the genus. The 

 lateral fasciole is, however, more or less discontinuous in the species. 



22. Pericosmus ISTelsoni, M'Coy, op. tit. pis. 66 & 67. 

 This is another well-marked species. 



23. Pericosmus compressus, M'Coy, op. tit. pis. 67 & 68, p. 21. 



This is a large and compressed species, and has a very close resem- 

 blance in shape to Megalaster compressus, nob. (Quart. Journ. Geol. 

 Soc. 1877, vol. xxxiii. p. 62). Supposing Megalaster compressus to be 

 a well-scrubbed fossil, from off which all traces of fascioles have been 

 worn, may it not be a Pericosmus, and is it not a worn Pericosmus 



