THE KED CHALK Or HU:j;rSTANTON. 



463 



1. Stomatopoea gracilis (Edwards). 



1838. Alecto gracilis, Edw. Ann. Sc. nat. (9) p. 207, pi. 46. f. 2. 



1848. Stomatopora gracilis, Bronn, Index Palaeont. p. 1202. 



1850. Alecto gracilis, Lonsd. in Geol. Sussex, p. 269, pi. xviii. A, 

 f.l. 



1852. Stomaiopora gracilis, D'Orb. Terr. Crct. v. p. 843, pi. 758. 

 f. 17, 18. 



1883. Stomatopora gracilis, Yine, Brit. Assoc. Rep. Eoss. Polyz. 



Zoarium delicate, wholly adherent ; branches dichotomizing 

 irregularly, and rather variable in breadth. Zooecia uniserial, origi- 

 nating from a disk-like base, from which two cells are generally 

 thrown off, and these form the nucleus of two distinct branches ; 

 cells slightly lateral at their points of juncture with the parent cell, 

 aperture circular, occasionally oval, even when not worn ; turning 

 alternately to the right and left, but sometimes pointing upwards. 

 Gonrecium ? 



Habitat. On Terebratula hiplicata, Bow., Inoceramus, &c. Fossil 

 jS'o. 1 A. There are several other colonies and species on this 

 specimen. 



Horizon. Red Chalk, Hunstanton. 



This is by far the most delicate aud most abundant of all the 

 uniserial StomatoiDorce in the Red Chalk of Hunstanton. It is not 

 always possible to make out the zooecial details, or ramifications, 

 of this interesting species on account of the secondary incrustations, 

 which very often obscure the delicate branches. I have, however, 

 been rather successful in defining several small colonies (one 

 with the basal originating disc), which were adherent on a variety of 

 fossils. The fossil marked No. 1 has on it many other colonies ; 

 and the same fossil bears the type species of Diastopora huustanton- 

 ensis, described further on. It may be well to keep the Red- 

 Chalk S. gracilis separated, as a variety, from the more robust form 

 found in the Upper Chalk. D'Orbigny characterizes the species as 

 the least in dimensions of all the uniserial Stomatopora^. known 

 to him, and he states that the diameter of the branches is 4- millim. 

 The branches of the Red-Chalk examples are, generally speaking, 

 of about the same dimensions, but others are more delicate. 



2. Stomatopora divaricata (Roemer). 



1840. Aulopora divaricata, Roem. Ool. ii. p. 15, pi. 17. f. 3. 



1841. Aulopora divaricata, Roem. Kreid. p. 18. 



1847. Alecto divaricata, d'Orb. Prod. ii. p. 175. 



1848. Stomatopora divaricata, Bronn, Index Palaeon. p. 1201. 

 1850. Alecto hrevis, d'Orb. Terr. Cretac. v. pi. 629. f. 16-18. 

 1852. Stoynatopora divaricata, d'Orb. Terr. Cret. p. 840, pi. 629. 

 1872. Stoynatopora divaricata, Reuss, Pliiner*, p. 112, pi. 28. 



f. 1, 2. 



Adherent to a large number of fossils, many of them species of 

 Inoceramus and Terehratida, is a blunt or stunted Stomatopora. 



* Bibliographic List, No. 10, ]), 458. 



