AUSTRALIAN CA1N0Z0IC (TERTIARY) DEPOSITS. 49 



Length ly 4 ^ inch, breadth ly2_ inch, height ^ inch. 



Locality. — Mbunt-Gambier Limestone. 



The smaller specimens are flatter ; in one the periproct is mar- 

 ginal, and in another supramarginal; their ambitus is blunter than 

 that of the large specimens. 



PETALOSTICHA. 

 Family NUCLEOLIDJE. 

 Ehynchoptgus dysasteroldes, sp. nov. Plate III. figs. 9 & 10. 



The outline of the ambitus from the actinal surfaco is ovoid, being 

 rounded and broad anteriorly and narrower and slightly pointed 

 posteriorly. This outline is less evident from the abactinal surface 

 on account of the keel which passes from the vertex posteriorly, and 

 of the slight roundness of the test on either side of it near the am- 

 bitus. The test is thick in substance, and in general shape is 

 rather depressed, but convex above and concave below. It is 

 arched from the front to behind the apical system, which is slightly 

 eccentric to the front, but is slightly flattened anteriorly, and to a 

 certain extent laterally above the ambitus. The arched shape is 

 not so decided posteriorly, where, near the vertex, the keel starts ob- 

 liquely backwards and downwards to overhang, at about one fourth 

 of the height, the small transverse periproct, which has a flat and 

 shallow groove. The greatest width is just behind the antero-lateral 

 ambulacra ; and the mouth and apical system nearly correspond, the 

 first being slightly more anterior than the other. 



The apical system is elongate; and the anterior and posterior 

 pairs of generative pores are wide apart, the ocular plates of the 

 antero-lateral ambulacra comiDg well in between them (PI. III. 

 fig. 10). Hence the posterior ; lateral ambulacra are more distant 

 than is usual in the Cassidulidse. The anterior generative pores are 

 large, closer together than the posterior ; and the madreporiform 

 body is small, convex, and reaches just in front of the right ocular 

 foramen. The posterior pairs of generative pores are wider apart 

 and slightly smaller than the anterior, and are posterior (by the 

 length of their own distance apart) to the ocular foramina of the 

 antero-lateral ambulacra. The rectangular space between the an- 

 terior and posterior generative pores is slightly depressed, the 

 madreporic body forming however an elevation in it. This space 

 is covered with miliaries and a few small tubercles. 



The ambulacra are long and narrow, being, with the exception of 

 the anterior, which is slightly in a groove, flush with the test. The 

 poriferous zones are lower, and are continued to the ambitus, the 

 distance between the pairs of pores gradually increasing near the 

 edge. 



The poriferous zones are narrow, and not so wide as the inter- 

 poriferous ; and the pores of the inner rows are round and smaller 

 than the oval and more or less elongate kinds of the outer rows. 

 They are conjugate. The pores of the odd anterior ambulacrum are 



Q. J. G. S. No. 129. e 



