318 Transactions of the Society. 



tended examination of the material in which these phenomena are 

 to be observed, and whether the creation of* new genera (Mlipso- 

 glandulina, Ellipsobulimina, Ellvpxopoliiniorphina) would be valid 

 in the absence of specific forms for which such generic names w^ould 

 appear to be required. All these " Ellipsoidiniform " types are so 

 rare, and so highly Localized, that it occurs to us that the whole 

 problem of their structure, and still more of their affinities, is still 

 a matter of conjecture, and one requiring more extended and par- 

 ticular research; and it appears to us that the creation of such 

 genera, pending such research, is likely to tend to confusion, and to 

 increase the difficulties which already beset the enquiry. 



Since reading Dr. Silvestri's papers we have made a further 

 study of considerable minuteness of such material as is available to 

 us, including transparent preparations of particularly well preserved 

 specimens, with the result that we find that the internal siphon is 

 not by any means a constant feature in Pleurostomella alternans 

 Schwager. It is sometimes entirely absent, although a superficial 

 observer might be misled by the refraction of the inner walls of 

 the chambers so far as to conclude that the inward siphon, as 

 figured by Beissel and Silvestri, is uniformly present. 



As to whether there are two distinct but isomorphic types, viz. 

 Pleurostomella devoid of siphon, and Ellipsopleurostomella, Silvestri, 

 (= Ellipsoidella Heron- Allen and Earland), in which the siphon is 

 normally present, or whether these two apparently distinct forms 

 are identical, i.e., that the siphon is a growth accessory to the 

 full development of the shell, we are not at present in a posi- 

 tion to express an opinion. We can only hope that the further 

 researches promised by Dr. Silvestri wall clear up this uncertainty, 

 and throw additional light on this interesting group of Ehizopods. 

 Pending such further investigations, it appears that our generic 

 name must be withdrawn in favour of Dr. Silvestri's earlier but, in 

 our opinion, less felicitous, title, Ellipsopleurostomella. 



104. Lagena lucida Williamson sp. 



(Plate X. fig. 16.) 



We figure a particularly fine double specimen which we have 

 found. Twin Lagenm are very uncommon, and, so far as our ex- 

 perience goes, double specimens are always joined mouth to base, as 

 in the figure, and not mouth to mouth as usual in plastogamic 

 specimens in other genera. The abnormality is therefore probably 

 due to budding, and not to true plastogamy. 



342. Lagena bicarinata Terqueni sp. 



Fissnrina bicarinata Terqueni, 1882, Mem. Soc. Geol. France, ser. 3, vol. ii. 



Mem. 3, p. 31, pi. i. fig. 24. 

 Lagena bicarinata (Terqueni) Balkwill and Millett, 1884, Journ. Micr. vol. iii. 



p. 82, pi. ii. tig. 4, and trifacial pi. iii. fig. 9. 



