256 W. D. Lang — Cheilostome Polyzoa. 



Fig. 



3. Holectypus hemisphcerims. Broadwindsor. Variant 1. 



4. ,, ,, Bridport. Variant 2. 



5. ,, ,, Broadwindsor. Variant 2. 



6. ,, ,, Broadwindsor. Variant 3. 



7. Discoides cylindricus. Wallingford. Normal apical system. 



8. Conulus subrotundus. Beigate. Cf. variant 1. 



9. Nucleolites orbicularis. Bushden. ? Normal apical system. 



10. Holectypus depressus. Bushden. Oculars I, II, and III "insert 



11. ,, ,, Same locality. All oculars " insert ". 



12. ,, oblongus. Upware. Normal apical system. 



IV. — On soio: new Cenomanian and Tctronian Cheilostome 

 Polyzoa. 



By W. D. Lang, M.A. 



(By permission of the Trustees of the British Museum.) 



(PLATE XVII.) 



Hapsidopora, new genus. 



(?) fiat's, ' an arch,' in reference to the hoop formed proximally to 



the aperture.) 



Diagnosis. — Asty incrusting, uniserial, with bilateral and unilateral 

 branching ; cecia dimorphic ; normal cecia with short caudse or without 

 caudse ; pyriform ; term en a complete, high, narrow, oval ridge with 

 few small spines on its circumference and, at the proximal-lateral 

 corners of the aperture, a pair of stout spines which sometimes, if 

 not always, bend towards one another and fuse in the middle line ; 

 apparently there are no spines around the distal end of the aperture ; 

 extra-terminal front-wall well-developed proximally, and arched ; 

 intra-terminal front-wall a wide, depressed lamina ; aperture oval, 

 sub-quadrate, somewhat constricted laterally ; avicularia small, one, 

 or a pair, placed laterally and somewhat distally with regard to each 

 aperture, rather abruptly pointed with the distal ends curved towards 

 the aperture they encompass ; ovicells hyperstomial. 



Genotype. — Hapsidopora arctiata, n.sp. 



Remarks. — It is noteworthy that the terminal ring of Hapsidopora 

 is complete proximally, and not smoothed away as in so many other 

 forms with a wide lamina. 



Key to the genus Hapsidopora. 



A. Pair of spines at the proximal-lateral corners 

 of aperture not so stout, and the terminal 

 spines proximal to these larger than in 

 II. arctiata . . . . . .I.E.. harmeri. 



P>. Pair of spines at the proximal-lateral corners 

 of the aperture very stout and arching over, 

 fuse with one another in the mid-line ; 

 terminal spines proximal to these smaller 

 than in H. harmeri . . . . . 2. H arctiata. 



