PEOBOSCTNA. 
39 
Figures. 
I PI. II. Fig. 3. Part of a zoarium. 'which has uniserial branches 
^ from a biserial stem ; X 12 dia. Middle Chalk: Chatham. Yine 
I Coll. D. 2683. 
PI. II. Fig. 4. Part of a zoarium in which the young branches 
I are Stomatoporiform with multiserial expansions ; X 6 dia. Middle 
Chalk : Chatham. Gamble Coll. D. 3798. 
PI. II. Fig. 5. Part of a reticular zoarium in which the distal 
branches are regular and triserial. Middle Chalk: Chatham. 
Gamble Coll. D. 3817. 
Affinities. 
I This variety is characterized by the great extent of its Stomato- 
I poriform portion. ^N^early all Froho&cinm pass through a Stomatopora 
stage, but in none is it so largely developed as in this variety. 
Its nearest ally is the variety francorum^ from which it is not 
easily separated ; but that variety has fewer uniserial zooecia, 
larger peristomes, and a more regular zoarium. The name of 
this variety is suggested from Alecto^ a well-known synonym of 
Stomatopora. 
The British Museum Collection contains a specimen from the 
Cenomanian of Le Mans, which closely agrees with this variety, 
and has affinities to var. elevata. Its exact position cannot be 
j safely determined from the single zoarium. 
I LIST OF SPECIMENS. 
1 British. 
D. 2683. A zoarium with raised peristomes and uniserial offshoots. Middle 
j Chalk. Chatham. Vine Coll. Figd. PI. II. Fig. 3. 
D. 3798. An irregular zoarium with many uniserial branches. Middle Chalk. 
Chatham. Gamble Coll. Figd. PI. II. Fig. 4. 
I D. 3817. A zoarium with one branch approximating to that of P. fasciculata. 
I Middle Chalk. Chatham. Gamble Coll. Figd. PL II. Fig. 5. 
D. 380. A zoarium encrusting a fragment of Inoceramus (on slide). Middle 
I Chalk. Chatham. Gamble Coll. 
i D. 3805. Encrusting an echinid fragment (on slide) . Middle Chalk. Chatham. 
' Gamble Coll. 
D. 3807. Encrusting an echinid fragment (on slide). Middle Chalk. Chatham. 
J Gamble Coll. 
D. 8808. Encrusting an echinid fragment (on slide). Middle Chalk. Chatham. 
Gamble Coll. 
D. 3799. A loose zoarium encrusting Echinocorys fragment. Middle Chalk. 
! Chatham. Gamble Coll. 
