328 Mr. F. Chapman on the 



a genus of the subfamily Trochamminince, and retained the 

 genus in the arenaceous series. Previous to the last-named 

 author Dr. Sollas, in 1877 *, finding certain Foraniinifera 

 resembling Wehhina in the Cambridge Greensand, but 

 exhibiting a tubulated structure in the shell-wall, proposed to 

 reserve Wehhina for the hyaline or perforate type of the 

 adherent monilifoim series of ovoid chambers, whilst the 

 truly arenaceous forms, such as W. clavata, P. & J., he 

 suggested should be relegated to the genus Trochammina. 

 This change would necessitate considerable alteration in the 

 accepted nomenclature of the group, and, further, would not 

 distinguish the adherent few-chambered forms from the free 

 many-chambered and coiled species, although such distinc- 

 tions are not necessary and, indeed, are not uniformly adhered 

 to in the classification of the Foraniinifera. 



To meet the difficulty arising from the existence of two 

 distinct types of Foraniinifera having the similar external 

 form but exhibiting a fundamental difference in the character 

 of the shell-wall, the writer proposed Vitriwehhina in 1892 t 

 as a genus, to include the species with a perforate type of 

 shell. In the same year Dr. Perner described specimens of 

 the perforate type of Wehhina which he had obtained from 

 the Cenomanian strata of Bohemia J. Tliese specimens he 

 referred to Trochani'nnna irregularis (P. & J.), Carpenter, 

 and remarked at the same time that it is doubtful if the other 

 species are imperforate §. 



From the long usage of the generic term Wehhina to 

 include the finely arenaceous forms with adherent pyriform or 

 rounded segments, according to the definition given by Jones, 

 Parker, and Brady in 1866, it now appears unnecessary to 

 revert to the types of the original authors, since the originator 

 of the generic term did not clearly define the limits of the 



* Sollas, W. J., " On the Perforate Character of the Genus Wehhina, 

 ■with a iietice of Tavo lbw Species, W. Icuvis and W. tuberculata, from 

 the CamLridge GreensaLd," Geological Magazine, dec. ii. vul. iv. [1877] 

 pp. 102-105, pi vi. 



t Chapmau, F., "Some uew Forms of Hyaline Foraniinifera from the 

 Gault," Geol. Mag. dec. iii. vol. viii. [189:2] pp. 5:2-54, pi. ii. 



I Peruer, J., " Ueber die Foramiuiferen des bohmischeu Cenomans " 

 [" Foran;inifery Cesk^ho cenomanu "], Ceska Akademie Cisare Frankiska 

 Josefa (Prague, 1892), Palseontographica Bohemias, no. 1, p. 63, pi. ix. 

 tigs. 1-0. 



§ Dr. Perner informs me that he has subsequently seen some of the 

 original specimens of Wehhina in d'Orbigny's collection, and finds that 

 they have a perforate phell-wall. I'his evidence alone would not, how- 

 ever, be sufficient fur ehtablishing the genus as one of the hyaline group, 

 since d'Orbigny included diflerent and distinct types in his series. 



41 



