522 PERONELLA PERONII. 



thicker and shorter radiating walls and pillars, which distinguish this species 

 from P. decagonalis, arc merely features greatly modified by age. Not to 

 introduce needless confusion, 1 give the points of difference between the 

 specimens. 



The outline is nearly circular; the edge of the test slightly swollen; the 

 abactinal surface slightly depressed at the extremity of petals, where the 

 tesl i> covered by huge glassy tubercles similar to those observed in the 

 young of C. subdepressus. Petals broadly lanceolate, extending more than 

 half-way to the edge; anterior pair slightly shorter than the others; porif- 

 erous zone narrow ; poriferous grooves sharply cut ; poriferous zone broadest 

 near the extremity of the petals ; four distant genital pores, one very indis- 

 tinct ; anus transversely elliptical, placed about three times its diameter 

 from the edge of the test. Ambulaeral furrows indistinct, extending only 

 a short distance from the actinostoine. 



Lour. Trans. Ant. Pair I' t Pair Hit Anus 



Diam. Diam. Petals. Petals. from Edge. 



23.8 22. 5. 5.4 3. 



Now Holland ; Formosa. 



Peromelia Peronii 



! Laganum Peronii Agass., 1841, Moo. Sent, p. 12.1. /'/. XXII. 

 ! Perouella Peronii Giiay, 1855, Cat. Rec. Ech., p. 13. 



n.xiir.f. 4-5. 



Professor Agassi/, first called attention to the striking differences existing 

 among the specimens of what had usually passed as Laganum orbiculare, 

 distinguishing the species with four genital openings situated in the apical 

 system (P. orbicularis) from the present species, usually confounded with it. 

 in which the genital openings (four) are placed in the ambulaeral spaces at 

 a considerable distance from the apex. The general outline is circular ; test 

 thick; edge slightly swollen ; the petals broadly lanceolate, similar to those 

 of P. orbicularis. The mouth transversely elliptical, placed at about one 

 third the distance between the edtje and the actinostoine from the former. 

 Tuberculation, as in P. orbicularis, distant, quite uniform on both the actinal 

 and abactinal surfaces. Ambulaeral furrows indistinct, extending but a short 

 distance from the mouth. The interior already shows the fan-shaped and 



