22 
PEOBOSCINA. 
narrow. The peristomes are flush with the surface of the 
zoarium, or slightly raised ; and they are usually distributed 
irregularly, hut are occasionally quincuncial or in transverse 
linear series. 
Type Species. 
P. loryi^ Audouin. 
Affinities. 
The reasons for the retention of this group have been given 
in the Cat. Jur. Bry. The decision has been approved by some 
students of the Bryozoa and censured by others. The great 
practical convenience of the adoption of this division of 
Tuhuliporidae seems to outweigh the criticisms made against its 
validity. 
The genus is very common in the Cretaceous, and is represented 
by a great variety of forms. Some species, e.g. P. angmtaia and 
P. hagenowi, are Stomatopoiiform ; some, e.g. P. dilatata and 
P. cornucopi(B^ are Bereniciform ; others, such as P. radiolitorum 
and P. anomala, are Idmoniiform ; others again, such as P. alternata, 
are Tubuliporiform. 
The Cretaceous members of the genus not only include a wide 
range of variations, but each member of the series is so variable 
that it is probably impossible to divide them into rigidly deflned 
species. Many students of the Bryozoa have referred to the 
difiiculty presented by this group. Thus, Hincks ^ remarks : “ it is 
extremely difficult in this tribe to find valid specific distinctions.” 
There is no agreement as to the most useful taxonomic character 
in this genus ; hence the divisions here accepted are to he regarded 
as convenient ‘ circuli ’ of individuals, rather than as sharply 
defined natural ‘ species.’ 
1. Proboscina angustata (d’Orhigny), 1851. 
Synonymy. 
Idmonea angustata, d’Orbigny, 1851. Bry. Cret. pi. 632, figs. 7-9. 
Froboscina ,, d’Orbigny, 1854. Ibid. p. 852. 
,, ,, Eeuss, 1872. Bry. unt. Plan. : Palseontogr. vol. xx. pt. 1, 
p. 113, pi. xxviii. fig. 34. 
1 Hincks: Brit. Mar. Polyz. vol. i. p. 431. 
