W. D. Lang — Cretaceous Cheilostome Polyzoa. 503 



Genotype. Distelopora bipilata, n.sp. 



Distribution. Cenomanian. 



Distelopora bipilata, 1 n.sp. PI. XVII, figs. 8 & 9. 



Diagnosis. As for the genus. 



Type-specimen. British Museum specimen D. 23019. F. Mockler 

 Coll. 



Distribution. Cenomanian, Chalk Marl, 10-20 feet from base; 

 N.E. of Cambridge. 



VI. A Key to the Cretaceous Uniserial Cheilostome Polyzoa. 



In two former papers 2 uniserial Cretaceous Cheilostomes have been dealt 

 with, and for convenience in determination a synopsis of the different genera 

 described is here given. 



A. Calcareous portion of intra-terminal front wall confined to a narrow bevel. 

 f I. No avicularia present. 



"a. Termen plain — no rhamma. 



(1. Uniserial with bilateral branching with wide angle of 



divergence . .- . . • Herpetopora. 



Cenomanian-Danian. 

 2. Pauciserial or uniserial with unilateral branching with 

 small angle of divergence .... Pyripora. 



Miocene. 

 b. Termen with beads or spines. 



1. No rhamma Allantopora. 



Danian. 



2. A rhamma present. 

 'a. Branching with wide angle of divergence ; caudse 



long ....... Rhammatopora. 



Aptian to Cenomanian. 

 /3. Branching with small angle of divergence ; caudas 



short or absent Charixa. 



Albian. 

 II. With avicularia. Termen with spines or beads. 



r 1 . Uniserial with bilateral branching throughout Marssonopora. 



Upper Senonian. 

 -I 2. Uniserial condition with bilateral branching only in 



early zoarial stages Mystriopora. 



v. Cenomanian. 



B. Calcareous portion of intra-terminal front wall consisting of a 



very broad bevel or lamina ; no avicularia ; later zoarial stages 

 multiserial with unilateral branching ; proximal terminal spines 



very large Distelopora. 



Cenomanian. 



C. Intra-terminal front wall entirely calcareous. 



. ■ . Dacryopora. 

 ? Cenomanian to Senonian. 



Fig. 

 1. 



EXPLANATION OF PLATE XVII. 



Rliammatopora vinei. Two zocecia of the type-specimen (the specimen 

 figured by Vine as Membranipora gaultina, Quart. Journ. Geol. Soc, 

 Vol. xlvi, PL xix, figs. 13 a-b). x about 25 diameters. British 

 Museum specimen No. D. 2051. Albian, Bed Chalk. Hunstanton, 

 Norfolk. T. Jesson Collection. 



Rhammatopora gaultina (Vine). Two zocecia and the cauda of a third 

 which has collapsed along the line of the rhamma. This structure is 



1 bi- prefix meaning ' two ' and pila ' a pillar '. 



2 Lang, 1914, Geol. Mag., Dec. VI, Vol. I, pp. 5 and 436. 



