Nomenclature of the Foraminifera. 337 



Fig. 9 is a smooth Lagena^, less globose than that shown by 

 fig. 6, and tapering gently to the neck. 



Fig. 8 is a smooth short-necked Lagena^, or rather represents 

 a specimen having no external, but an internal neck-tube, — a 

 form known as Entosolenia (Ehrenberg). Fig. 7 represents the 

 Entosolenia marginataX, a compressed Lagena with intussus- 

 cepted apertural tube. The relations of the externally and the 

 internally tube-necked Lagence are so close that we cannot regard 

 them as forming two distinct specific types. To this opinion we 

 strongly bent in the paper on the Norway Foraminifera § ; ancf 

 we feel far more convinced by subsequent observations. 



For the reasons which guided us in the consideration of No- 

 dosaria (Ann. N. Hist. 3rd ser. vol. iii. pp.476, 478) we regard 

 Lagena sulcata as the type of the species. It exhibits essential 

 features of form and ornament. Rib-patterns appear abundantly 

 on these single-celled Foraminifers, and on their polythalamoiis 

 congeners, the Nodosarice and Uvigerina, and much less strongly 

 on the Polymorphince, which are also related, but more particu- 

 larly, to the Entosolenian group. The reticulate ornament, 

 formed by minute transverse concentric ridges uniting the 

 parallel ribs, or by sinuous riblets anastomosing with each 

 other, is more specially a feature in the latter group, though 

 traces of it are occasionally to be found on the typical L. sulcata. 

 The marginate condition obtains both in Entosolenian and Ecto- 

 solenian forms. The extrusion and intrusion of the aperture- 

 tube occur to an exceedingly variable extent, and are often com- 

 bined. The modifications of this feature are too numerous to 

 be here described. We may remark that both Ectosolenia and 

 Entosolenia often have tubes at each end of the shell ; and occa- 

 sionally there is a second internal tube attached to the side of 

 the interior, appearing as though the tube had been broken off 

 and its fragment had become attached during life. The Lagena 

 are occasionally elongate and spindle-shaped, with an aperture 

 at each end; these slender individuals are sometimes bent. 

 Professor WilUamson figures the section of a double or twin 

 specimen of Entosolenia, in which two individuals had grown off" 

 divergently from the primordial cell. 



Prof. Williamson prefers the smooth form || as a representa- 

 tive of the type, but objects to use as a specific name the term 

 " Isevis," expressive of the absence of ornamentation, inasmuch 

 as, in this case, the varietal names, alluding to the ornament, 



* " From Sandwich ; very rare." f " Froin Sandwich ; very rare." 



X " From the Reculver ; very rare." 

 § Annals Nat. Hist. 1857, vol. xix. 



II In our paper on the Norway Foraminifera (Ann. N. H. 1857, vol. xix. 

 p. 278) we also took this as the type. 



Ann, ^ Mag, N. Hist. Ser. 3. Vol'w. 22 



