CCELOPTYCHIUM. 147 



1877. Cosloptychium agaricoides, Zitt. Studien^ I Ab. p. 59; Neues Jahrbucli, p. 371. 



1878. Cosloptychium agaricoides, Zitt. Handbuch der Pal. Bd. 1, p. 184, f. 100. 

 1878. Cceloptychium longostiwn, Quenst. Petref. Bd. 5, p. 519, t. 140. f. 1, 2. 



In addition to very perfect examples of this species from the Upper Chalk of 

 Westphalia, the Museum possesses a small specimen from the Upper Chalk of this 

 country which may be referred to this species, though, as the characters of the under 

 .surface are concealed, it is doubtful whether it belongs here or to C. deciminum. 

 The specimen in question is without a stem ; the body is 50 mm. in width and 8 in 

 thickness. The upper surface is flat with a central depression, the margins are 

 sharp and slightly elevated. The surface is for the most part composed of a coarsely 

 reticulate mesh with radiating bands of a finely punctate character. The interior 

 folds of the wall are about "9 mm. in thickness. 



Distrihution. Upper Chalk : Coesfeld, Westphalia ; Lemforde, Hanover [coll. 

 Zitt.); South of England ; Norwich {S. Woodward). 



Cceloptychium deciminum, F. A. Boemer. 



1841. Cceloptychium deciminum, Roemer, Nordd. Kreide, p. 10, t. 4. f. 3. 



1865. Cceloptychium Belfastiense, Tate, Quart. Journ. Geol. Soc. vol. xxi. p. 43, t. 5. f. 7. 



1876. Cceloptychium deciminum, Zitt. Abhand. k. bayr. Ak. II CI. Bd. 12, p. 62, t. 1. f. 6, 7, 

 and t. 3. f. 2. 



1877. Cceloptychium deciminum, Zitt. Studien, I Ab. p. 59; Neues Jahrbucb, p. 371. 



The only example in the collection which I refer to this species is the upper 

 portion of a specimen from the Norwich Chalk, which is 114 mm. in width and 15 

 in thickness. The upper surface appears to have been flat or gently concave ; its 

 minute structure is not shown. On the ridges of the under surface are small circular 

 or oval apertures, 1*2 mm. in width. The folds of the interior of the wall are 

 1*6 mm. in thickness; they are built up of an extremely regular spicular mesh, with 

 octahedral nodes '44 mm. apart. 



The fragment of a specimen from the indurated chalk of Belfast, named by Tate 

 Coeloptychium Belfastiense, appears to me to belong to this species. Only the 

 ridges of the under surface are preserved ; these are about 6 ram. in width ; they are 

 furnished with small circular oscular apertures 1 mm. in diameter. The spicular 

 structure has been obliterated. The specimen is in the Jermyn-Street Museum. 



Distrihution. Upper Chalk : Norwich {coll. Bayfield) ; Belfast, Ireland. 



CCELOPTTCHIUM FUKCATUM, Tate. 

 1865. Cceloptychium furcatum, Tate, Quart. Journ. Geol. Soc. vol. xxi. t. 5. f. 6. 

 This species is founded on a fragment of the body of a specimen, showing the 

 ridges of the under surface, which openly bifurcate. A few oval oscular apertures 



u 2 



