52 P. M. DUNCAN ON THE ECHINODERMATA OE THE 



generative pores. The anterior ambulacrum is in a shallow groove, 

 and its small pores, rather crowded above, become more distant and 

 larger towards the ambitus ; they are oblique in direction, round, and 

 nearly equal, in pairs, being separated by a very delicate septum. 



The pores of the antero -lateral ambulacra are small, equal, 

 round, and wider apart and larger towards the ambitus, where the 

 zones are wide apart. The posterior pair of ambulacra are rather 

 close together, and the pores resemble those of the others. The 

 periproct is small and situated in the truncated posterior part. The 

 actinosome is at the anterior third ; it is sunken, transverse, and 

 the posterior lip passes into a prominent keel-like plastron. The 

 ornamentation is very simple : there are no large or even secondary 

 tubercles ; but small tertiaries and miliaries exist, generally scattered. 



Length 1^- inch, greatest breadth a line or two less ; height in 

 front T 7 ^ and behind -^ inch. 



Locality. — No. 5, Upper Coralline Beds, Castle Cove, Cape Otway. 



Maretia anomala, sp. nov. Plate IV. figs. 1-4. 



The test is thin, depressed, and the outline from above is irregu- 

 larly oval and rounded anteriorly. There is a slight indentation at 

 the ambitus, made by the shallow anterior groove ; and the shape is 

 rather angular posteriorly in the anal region, and broadest midway. 

 The sides of the test are sharply rounded, slightly angular. The 

 abactinal surface is highest posteriorly on account of the anal keel, 

 which, being produced backwards, is also sloped and depressed ante- 

 riorly between the posterior petals. The apical system is small, and 

 the four large genital openings are close to each other (PI. IV. fig. 1), 

 the madreporiform body passing backwards ; it is in advance of the 

 centre and anterior to the depression already noticed. The anterior 

 and shortest petaloid ambulacra are lanceolate, and are almost 

 transverse. The poriferous zones slope up to raised, broad inter- 

 poriferous zones ; and the external rows of pores are the largest, 

 and usually more oval than round. The posterior rows are better- 

 developed than the anterior, which are imperfect near the apical 

 system. About 21 rows of pores exist, all of which are conjugate. 



The posterior ambulacra are long, broad, flush, and wider 

 posteriorly than anteriorly; they are nearly parallel with each 

 other, and bound the keel on either side. The external pori- 

 ferous zones are curved ; the internal are much less so ; and the 

 interporiferous zones are much broader than those of the antero- 

 lateral petals, and there are traces of two or three large secondary 

 tubercles within their area. The odd anterior ambulacrum is nearly 

 flush with the test, except at the ambitus, where there is a slight de- 

 pression ; its pores are numerous near the apical system, and are 

 very small ; elsewhere they are very rare. This ambulacrum is bounded 

 externally by plates rather raised above the general level ; they are 

 tuberculate with large crenulate and perforate miliaries, and they 

 separate it from the plates with the large tubercles of the anterior 

 mterambulacra. The anterior interambulacra have several horizontal 

 rows of large and of secondary tubercles mixed and increasing in 





