24 
PEOBOSCINA. 
Dimensions. 
Pergens. 
B.M., 50,470. 
Average width of a branch 
— 
•5 mm. 
Length of zocecia 
•3-’4 mm. .. 
. ... -7 „ (-6--9) 
Diameter of zocecia 
•12--15 „ .. 
. ... -2 „ 
Diameter of aperture 
•03--04 „ 
. ... -1 
Disteibution. 
British : 
Upper Chalk : Bromley ; Margate. 
Middle Chalk ; Chatham. 
Upper Greensand : Isle of Wight. 
P Bed Chalk : Hunstanton. 
Foreign : 
Senonian — Campanian: Riigen ; ? Mecklenburg (from Drift). 
Santonian : Cachembach, near Chartres. 
Turonian : St. Rimay, Loir-et-Cher. 
Arrialoor Series : Poodoopolliam, S. India. 
Cenomanian : Le Mans and St. Calais, Sarthe ; Rank, Jine, and 
Kamajk, in Koiycaner Schichten, and Bezdekau, near 
Randnitz, in Teplitzer Schichten ; Saxony, in Lower 
Planer. 
Figures. 
PI. II. Fig. 1. A zoarium encrusting an echinid fragment, 
X 7 dia. Upper Chalk : England. 50,470. 
Affinities. 
This group of ProloscirKB includes a series of specimens with 
long, narrow branches, which are generally biserial or triserial. 
D’Orbigny divided it into two species, calling the biserial forms 
P. angustata and the triserial forms P. rugosa. But as Pergens 
has pointed out, one branch of the type-specimen of P. rugosa 
is only biserial, so that the distinction is of little value ; and 
I accordingly follow Pergens in uniting them. In consequence 
of this decision Slovak’s P. intermedia must enter the same 
specific group. Novak remarks the close resemblance of his 
specimens to P. angustata ; but he separated them by three 
characters, the smaller diameter, smooth surface, and biserial 
zoarium of P. angustata. But Pergens’ measurements of 
d’Orbigny’s types show that the supposed difference in size 
does not hold; moreover, he tells us that the surface is “some- 
times transversely striate,” so that the second point is useless. 
