EUPATAGUS VALENCIENNESII. 573 



flush with the test. Genital openings four in number, close together ; poste- 

 rior pair slightly diverging at the anterior extremity of the madreporic body, 

 which extends into the posterior interambulacral space ; ocular spots forming 

 a large pentagon, enclosing in the central part tbe genital openings. Peri- 

 petalous faseiole broad, elliptical, running round the extremity of the lateral 

 petals and across tbe odd ambulacrum, slightly above the ambitus. The tu- 

 berculation of the abactinal surface is uniform below the peripetalous 

 faseiole ; the tubercles are distant, becoming more closely crowded towards 

 tbe ambitus and near the anterior extremity. There are from three to five 

 large isolated tubercles in the posterior interambulacral spaces above the 

 faseiole, from two to three similar large tubercles in the anterior interambu- 

 lacra next to the petals, and on each side of the odd ambulacrum a num- 

 ber of somewhat smaller tubercles, arranged in irregular transverse rows. 

 The edge of the test is rounded ; the actinal surface is flat, with the exception 

 of tbe slight keel formed by tbe posterior extremity of the interambulacral 

 actinal plastron ; the mouth is slightly sunken at the anterior extremity. 

 The actinal anterior and posterior lateral ambulacra form short bare avenues, 

 while between the lateral posterior interambulacra and the posterior end 

 of the plastron the posterior ambulacra form broad, bare, smooth bands, ex- 

 tending to the subanal faseiole and to the anal system. The subanal fasei- 

 ole is closed, heart-shaped, broad, with an indistinct anal branch. Seen in 

 profile, the test arches regularly to the vertex, which is anterior to the apical 

 system, then runs in a nearly horizontal line to the slight crest extend- 

 ing above the anal system. The anal system is large, pyriform, situated in 

 the vertically truncated posterior extremity, of which it occupies nearly the 

 whole space. From the edge, towards the actinostome, the tuberculation 

 becomes gradually more distant and coarser ; it is of uniform size, smaller 

 and closer than in the rest of the actinal side in the actinal plastron, except 

 on the keel. In the subanal plastron it forms diverging rows, becoming 

 smaller towards the faseiole, radiating from a small, nearly bare space. 



In dried specimens the spines are of a grayish color with silvery lustre, 

 curved, stout ; the spines of the larger tubercles and of the actinal side do 

 not differ from those of the abactinal side, otherwise than in being longer 

 and more curved at the base. The spines of the subanal plastron form a 

 well-marked, pointed tuft. The actinostome is large, nearly circular, with a 

 small labiate posterior edge ; the buccal membrane is strengthened by a 

 pavement of small, irregularly circular, limestone plates. 



Australia. 



