240 



CATOPYGUS 



family 9 — Echinobrissid^, Wri(/]d, 1856. 



Test thin, circular, oblong, sub -pentagonal, or clypeiform, covered with microscopic 

 perforate or imperforate tubercles, surrounded by excavated areolas ; ambulacra narrow, 

 enclosed by poriferous zones more or less petaloidal ; pores set at different distances apart, 

 and imited by connecting sutures. Mouth-opening small, nearly central, pentagonal, 

 edentulous, and in general surrounded by five lobes. Vent-opening in a sulcus in the 

 upper surface of the single inter-ambulacrum, or in a marginal depression or basal 

 portion thereof; apical disc small, with four perforate and one imperforate genital plate ; 

 ocular plates very small ; madreporiform body extending into the centre of the disc. 

 This family is extremely numerous in genera and species ; two of its representative forms 

 are still living — Echinobrissus recens, Edwards, in the Antilles, and Cassidulus Australus,. 

 Lamarck, in the Australian seas. 



I include the following genera in this natural family : 



Catopygtjs, Agassis. 

 Clypeopygus, d" Orbi(/ny. 

 Clypeus, Klein. 

 Echinobrissus, Breyniiis. 

 Phyllobrissus, Cotteau. 



BoTRioPYGUS, d' Orhigny. 

 Trematopygus, d'Orbiyny. 

 Rhynchopygus, d' Orbiyny. 

 Cassidulus, LamarcJc. 

 Caratomus, Jyassiz. 



Genus — Catopycus, Jyassiz, 1837. 



NucLEOLiTES, Lamarck, Goldfuss. 



JDiaynosis. — Test oval or elongated, in general inflated, narrower anteriorly than 

 posteriorly ; upper surface convex, summit excentrical anteriorly ; under surface flat or 

 slightly convex, and rounded at the border ; posterior half of the test much higher and 

 wider than the anterior half; vent situated in the posterior border; periprocte small, 

 round, or oval, placed high in a prominent projection of the inter-ambulacrum at the summit 

 of a vertical truncation of the area. Mouth-opening small, situated nearer the anterior 

 than the posterior border ; pentagonal in form with equal elongated sides, having one angle 

 anterior, and surrounded by five prominent lobes (PI. LV, fig. 2 h) ; between the lobes 

 a rosette is formed of five depressed leaves, crowned with minute granules and unequal 



