Dr. G. J. Hincle — Dkcovery of Marsiqrites, etc. 485 



are now replaced by iron peroxide, and consequently they are in 

 bad preservation. In addition to the species recognized, there are 

 fragments of Tetractinellid, Lithistid, and Hexactinellid forms, but 

 too imperfect even for generic identification. Calcisponges are not 

 so common, but are better preserved. Porosphcera is represented by 

 specimens from 2 to 18 mm. in diameter. 



EcJiinoidea. — Echinocorys scutatus, var. pyramidatus, is the pre- 

 dominant sea-urchin, and it occurs throughout the section, but more 

 abundantly in association with Marsiipites. The large depressed or 

 dome-shaped form of E. scutatus, the var. striatus, is less common, 

 Micraster cor-anguinum occurs at both ends of the section, but it is 

 somewhat rare. Galerites globulus is rare, and I have only met with 

 it near the south end of the trench. Galerites alhogalerus (==comcMs) 

 does not seem to be present in the road section, though it is not 

 uncommon in the Chalk of a road cutting a little further to the south 

 of the present one. 



Asteroidea. — The detached marginal ossicles of this group are 

 present in all parts of the section, and they probably belong to 

 several species. 



Bourgeticrinus elUpticus. — The cylindrical and barrel-shaped stem- 

 joints are frequent; usually single, but occasionally two are con- 

 nected together; the heads of this species are rare. The peculiar 

 nipple-shaped heads of another species of Bourgeticrinus, figured by 

 Dr. Eowe,^ but apparently not yet named, are occasionally found. 

 Dr. Eowe states that he has not found this form outside the 

 Marsupites-zone. 



Marsiipites testudinarius. — Detached plates of the test occur in 

 various parts of the road section ; they are fairly numerous at the 

 higher south end between the Keeper's House and the end of the 

 trench, and also near the north or Beddington end, below the New 

 Barn Farm, whilst in some of the intermediate portions, where 

 Uintacrinus plates are abundant, I have failed to find any of 

 Marsiipites. No complete specimens have as yet been discovered 

 in this Chalk, but not unfrequently several plates occur in close 

 proximity, as if they had belonged to a single individual. There 

 are notable differences in the size and ornamentation of the plates 

 from different parts of the section ; thus, at the south end the plates 

 are large and thick, reaching a maximum of 32 mm. in width, and, 

 as a rule, they are strongly ribbed or striated, whilst those met with 

 at the northern end are relatively thin and not over 14 mm. in 

 width, and their upper surfaces are quite smooth, with occasionally 

 a low fold near the margins. The brachial joints of Marsiipites are 

 rare, they are considerably larger than those of Uintacrinus, and they 

 differ also in form and in the ornamented exterior surface. 



Uintacrinus sp. — The irregularly polygonal plates of the test are 

 fairly numerous, more particularly in those parts of the road section 

 between the Keeper's House and the New Barn Farm, where 

 Marsiipites seems rare or absent. Only single detached plates are 



1 Proc. G-eol. Assoc, vol. xvi (1900), p. 297, pi. viii, fig. 6. 



