FROM THE UPPER CHALK. 



137 



CrPHosoMA MAGNiFicuM, Agassiz, 1840. PI. XXV, figs. \,% a,h, c, d, e. 



Ctphosoma MAGNiFicuM, Agussiz. Catal. Syst. Ectyp., p. 11, 1840. 



— SULCATUM, Agassiz et Desor. Catal. raison. des Schinides, p. 3.51, 



1846. 



— MAGNIFICUM, Bronn. Index Palaeontol., p. 381, 1848. 

 Phtmosoma — Desor. Synops. des Echinides foss., p. 88, 1856. 



— SULCATUM, Desor. Ibid., p. 90, 1856. 



CxPHOSOMA MiDDELTONi, Woodwurd. Meoi. Geol. Surv., Decade V, App., p, 4, 1856. 



— SULCATUM, Pictet. Traite de Paleontol., 2eed., t. iv, p. 243, 1857. 



— — Cotteau et Triger. Echinides de la Sarthe, pi. 44, fig. 9, 



1860. 

 Coquand. Synops. des Foss., Bull. Soc. Geol. de France, 



t. xvi, p. 992, 1860. 

 Dujardin et Hupe. Hist. Nat. Zoopb., p. 508, 1862. 

 Bourgeois. Especes Ter. Cretaces, Bull. Soc. Geol. France, 



deux, ser., t. xix, p. 674, 1862. 

 Cotteau. Echinides foss. des Pyrenees, p. 25, 1863. 

 Cotteau. Paleontologie Francaise ; Ter. Cretace, t. vii, p. 



635, pis. 1155-56-57,1865. 



Phymosoma — 



Phtmosoma — 

 Cyphosoma — 



— magnificum, 



Test circular, elevated, sides tumid, base concave ; poriferous zones narrow, undulated, 

 pores unigeminal ; primary tubercles of both areas large at the base and ambitus, and 

 small on the upper surface ; areolae large and confluent at ambitus and base^ very small 

 above; npper third of inter-ambulacra bordered with a row of small secondary tubercles; 

 miliary zone wide, sulcated, and nude above ; mouth-opening small, peristome equal- 

 lobed; discal opening very large, pentagonal, angular, and elongated. 



Dimensions. — a. Figured specimen, latitude ten lines ; altitude six lines. 



B. Specimen in my cabinet, latitude one inch ; altitude half an inch ; discal opening 

 (antero-posterior diameter) six tenths of an inch. 



Description. — This very rare British Cyphosoma was obtained by J. Middleton, Esq., 

 from the Upper Chalk, near Norwich, and placed in the hands of the late Professor Edward 

 Forbes for description, whose manuscript name for the same was C. Middeltoni. Under 

 this designation a diagnosis of the species was given by my late friend Dr. Woodward, 

 in his valuable appendix to Decade V of the 'Memoirs of the Geological Survey,' who 

 kindly obtained another specimen, to enable me to give a detailed description of this rare 

 British form ; a careful examination of this fossil, however, has satisfied me that it is 

 merely a small variety of Cyphosoma magnijicum, Agassiz, and agrees in all its specific 

 characters with the sulcate variety of that species. 



The test is circular, elevated, or moderately depressed on the upper surface, inflated at 

 the sides (PI. XXV, figs. 1 a and d) and concave at the base (fig. 1 c). The ambulacral 



18 



