in the South English Chalk. 367 



Terehratulina Rowei and Echinocorys scutatus, var. truncatus, have 

 disappeared apparently for good, and Offaster pilula though theoretically 

 a possibility is in practice absent, the other leading fossils of the sub- 

 zone of abundant 0. pilula have lives of varying but probably always 

 brief duration in the base of this zone. Ostrea canaliculata, var. striata, 

 for instance, is strongly represented in the lowest 6 feet and then 

 apparently disappears completely, Bourgueticrinus Forms 1 and 2 

 continue to occur sparingly for about 12 feet (accompanied by 

 transitions to forms wbich establish themselves later) and then 

 disappear. \_Bourgueticrinus Form 3 I think must be withdrawn 

 from the list of characteristic forms of the subzone of abundant 

 0. pilula. It is specially abundant in that subzone, but both appears 

 before it and persists in occasional instances long after it, and can 

 only be treated as a subsidiary guide fossil, for which a subzone so 

 strongly characterized has no need.] Mr. Spencer's remarks^ as to 

 the affinity of giant ossicles of Metopaster Parki^isoni and Calliderma 

 Smithicb for the zone of 0. pilula (sub 7iom. "subzone of 0. pilula") 

 and the lower beds of the zone of A. quadratus {sub nom. "subzone 

 of A. quadratus'''') give interest to the question exactly how far up 

 the zone of A. quadratus these forms range. The giant ossicles of 

 Metopaster Parkinsoni seem to culminate at from 26 to 33 feet ; only 

 one has been found yet above this level, i.e. at about 43 feet. They 

 have never yet been found in the upper part of the zone. The large 

 ossicles of Calliderma Smithice similarly referred to- have not been 

 found more than 12 feet up. 



The only striking feature is Hagenoivia rostrata. This fossil sets 

 in as soon as the zone of 0. pilula has ended and becomes sufficiently 

 abundant to serve as a guide fossil. Unfortunately the body of the 

 urchin is never preserved, the rostra having at most a little film of 

 shell attached. It is interesting to note that a rostrum has recently 

 been found in this zone, apparently for the first time in Hants, at 

 Compton, near Winchester, and in precisely the same relative position 

 in the zone. 



Belemnites are very scarce in the zone of 0. pilula except perhaps 

 at the base, where A. gratiulatus occurs sparingly but fairly 

 consistently. It is therefore only where there is a large area 

 available that there is any prospect of obtaining, even in the course 

 of years, enough specimens to afford any clue to the range of the 

 various species in that neighbourhood. The Sussex coast-section of 

 the zone is the only one which fulfils this condition, and it will not 

 be out of place to give the Belemnites at this point the special 

 consideration which they have earned by their value as zonal guides 

 elsewhere. 



Experience prepares lis for the occurrence of ioxir Belemnites, 

 A. gratiulatus, A. quadratus, A. verus, and Belemnitella lanceolata. 

 Of these B. lanceolata and A. verus have not been found yet, except 

 for an imperfect Belemnite at the top of the zone of P^. scutattis, var. 

 depressus, which may have been A. verus, and they are only likely to 



^ W. K. Spencer, "The Evolution of the Cretaceous Asteroidea " : Phil. 

 Trans. Eoy. Soc. Lond., ser. B, vol. cciv, p. 112. 

 " W. K. Spencer, op. cit., p. 218. 



