284- Messrs. W. K. Parker aud T. Rupert Jones un some 



for new names, and is sometimes even distinguished as a generic 

 character*. 



Fig. 34. PI. XI. represents a loose specimen of the cervicorn 

 tube. Fig. 25. PL X. shows the Polymorphina from which this 

 branched calcareous appendage was broken. It is to be remarked 

 that the terminal and some of the preceding chambers opened 

 laterally into the overlapping base of the tube by more than one 

 aperture, whilst the chief aperture has become plugged up (ex- 

 cepting perhaps its radiating slits) with calcareous matter, as is 

 not uncommonly the case with adult specimens of other species. 

 (See also fig. 5. PI. X.) 



Polymorphina is for the most part smooth externally, but 

 not unfrequently scabrous or roughish, tuberculate or aciculate, 

 and occasionally bears fine, parallel, shortish riblets (Australia). 

 The superficial aciculre or points appear sometimes to be minute 

 exserted tubules. None of these exogenous characters can be 

 regarded as of specific value, and they may or may not be pre- 

 sent on any variety of form. 



This shell occasionally loses its usual translucency or hyaline 

 character, and becomes more or less opake ; but we have never 

 recognized it in a sandy condition f. The common forms vary 

 extremely in size. 



We have found Polymorphina represented by its chief varieties 

 in the Chalk-marl, and more rarely in the Chalk. It is extremely 

 plentiful in very many of the Tertiary deposits (Grignon, Tours, 

 Bordeaux, Palermo, &c.), also in the post-tertiary clays of Lin- 

 colnshire, and in the recent sea-sand from every coast. 



The Norway specimens are undistinguishaljle from numerous 

 individuals from the European and other coasts, and even from 

 Southern Australia. 



6. Spirillina vivipara, Ehrenberg. PI. XI. fig. 46. 



Spirillina vivipara, Ehrenb. Berlin Trans. 1841, pi. 3. f. 41 ; ib. 1847, pi. 2. 



f. 82? 

 Cornuspira perforata, Schultze, Organ. Polytli. p.41.])l. 2. f. 22. 



Shell flat, spiral, like a minute Planorbis ; not presenting any 

 internal subdivisions, but being monothalamous. The little, ele- 

 gant, discoidal shell here figured is hyaline, and perforated with 

 rather large pseudopodian passages |. 



There are at least two other discospiral monothalamous Fora- 



* Hence "Aulostomella" of Alth, Haid. Abhandl. iii. p. 263. pi. 13. 



fig- 17. 



t Schultze's so-called Polymorphina silicea (Ueber den Organ. Polytli. 

 pi. 6. fig. 10) apjiears not to belong to the Polyworplmice. 



X See Williamson " on some Mud from the Levant," &c., Mem. Manch. 

 Phil. Soc. viii. p. 45. pi. 2. L 34. 



