1909. ] IN BRITISH SPECIES OF CORALS. 305 
even more advanced type of adult costa than P. cylindrica, in the 
elimination of costal-stages VII. and VIII. from all but the most 
proximal part of the corallum ; yet on the peduncle more primitive 
stages are shown than even P. mantelli exhibits, and in this 
P. monilis forms a link between P. gravest (as Duncan interpreted 
it) and P. mantelli. 
Text-fig. 46. 
ae PARASPILIA 
/STONILIS , DUNCAN. 
— RESUVENESCENCE. 
CYLINDRICAL STAGE. 
— KESOVENESCEWCE .- 
ae CYLINDRICAL 
G. STAGE 
Bs SRESUVENESCENCE 
Gua 
= TROCHOLD. 
STAGE. 
E.. 
/DY. 
a. PEDUNCLE STAGE . 
TU 
Costal stages in P. monilis Duncan. 
B.M. no. R. 6477. x3. 
At the base of the peduncle the costz are low and rather rough 
(text-fig. 46, A, costal-stage [V.), but rapidly heighten (text-fig. 46, 
B& C, costal-stages V. & VI.). In this, the Etched Period, the 
primary cost are longitudinally split (cf. P. granulata and P. 
gravest). At the lowest part of the Trochoid shape-stage the costa 
are low with few large granules (text-fig. 46, D, costal-stage VIL). 
These immediately mass together and the costze rise in height (text- 
fig. 46, H, costal-stage VIII.) and by the time the mid-Trochoid 
shape-stage is reached, the granules have entirely vanished, the 
coste are high with a thin, somewhat wavy ridge, and intercostal 
dissepiments have appeared (text-fig. 46, F’, costal-stage [X.). A 
