REPORT ON THE RADIOLARIA. 



clxv 



are related to those forms which are found in the recent Radiolarian ooze of the depths 

 of the Pacific, especially to the species which are characteristic of the Challenger Stations 

 225, 226, 265 and 268. Many living genera and families (e.g., most Larcoidea and 

 Stephoidea) have not yet been found in the Tertiary formations. 



A. The famous Polycystine marl of Barbados in the Antilles, which Robert Schomburgk dis- 

 covered forty years ago, belongs to the Miocene formation, and is the richest and best known of all 

 the unportant Eadiolarian deposits (see L. jST. 16, pp. 5-8). After Ehrenberg had pubhshed in 

 December 1846 the first preliminary communication regarding its composition out of masses of 

 well-preserved Polycystina, he was able in the following year to describe no less than 282 species 

 from it; he distributed these in 44 genera and 7 families (L. N. 4, 1847, p. 54). In the year 

 1854 Ehrenberg published figures of 33 species in his Mikrogeologie (L. IST. 6, Taf. xxxvi.) ; 

 but it was only in 1873 that he published descriptions of 265 species (Monatsber. d. k. preuss. 

 Akad. d. Wiss. Berlin, Jan. 30, pp. 213-263). Finally there followed in 1875 his Fortsetzung der 

 Mikrogeologischen Studien, mit specieller Eiicksicht auf den Polycystinen-Mergel von Barbados 

 (L. N. 25). On the thirty plates which accompany this the last work of Ehrenberg, 282 species 

 are figured and named, of which 54 are Spumellakia (13 Sphsroidea, 8 Prunoidea, 33 

 Disco idea), and 228 N"assellaria (2 Stephoidea, 38 Spyroidea, and 188 Cyr- 

 toidea). The fourth section of this memoir contains a survey of the Polycystine formation of 

 Barbados (pp. 106—115), and the fifth section the special description of a large sjDecimen of rock 

 from Mount Hillaby in Barbados (see also L. N. 28, p. 117, and L. N. 41, pp. 476-478). The 

 account given by Ehrenberg of the Polycystina of Barbados is in many respects very incomplete, 

 and very far from exhausting this rich mine of remarkable forms. This may be readily seen from 

 the twenty-five plates of figures of Polycystins in the Barbados Chalk Deposit published by 

 Bury in 1862 (L. N. 17). The number of species here figured (140 to 142) is about half of those 

 given by Ehrenberg ; and there are among them numerous generic types, some of great interest, 

 which were entirely overlooked by the latter; e.g. Saturnalis (Sphferoidea), Canimrtidiwni 

 (Prunoidea), Tympanidium (Stephoidea), Cindapyramis (Cyrtoidea), &c. Finally, 

 Ehrenberg always (until 1875) ignored Bury's atlas, which had been pubhshed thirteen years ago 

 and was quite accessible to him. How different were the contents of the two works may easily be 

 seen from the following abstract. 



Comparative View of the Species of Fossil Badiolaria from Barbados made known hy tJie figures 

 of Bury in 1862 and of Ehrenberg in 1875. 



