294 Messrs. W. K. Parker and T. Rupert Jones on some 



losing themselves in a wide-spread flat form, consisting of nume- 

 rous chambers, sometimes with somewhat of a cyclical mode of 

 growth {Plcuiorbulina^), at others with a very variable arrange- 

 ment of the chambersf [T. variabilis, D'Orb.)- In both of these 

 flat forms ( Truncatulina and Planorhulina) the shell is affixed to 

 fronds of sea-weeds and to shells. 



In another condition of growth also {Acervulina I, including 

 perhaps Rosalina globuUiris, D^Orb.) it enwraps small stalks of 

 sea-weeds and polyparians. 



This is a world-wide species : it is common in the Tertiary 

 deposits ; and is found also in the Chalk. It is numerous in 

 all the Norway dredgmgs. 



18. Anomalina^ coronata, nov. sp. PI. X. figs. 15, 16. 



This shell has the general aspect and beai-ing of the common 

 Truncatulina ; but it is not depressed, and afl'ects a bilateral 

 synmietry, the two surfaces being often nearly equal. The 

 umbilici are deeply and broadly sunken ; the convexity of the 

 chambers forming an almost ridge-like corona on each face of 

 the shell. The aperture is a transverse chink at the base of the 

 chamber (as in Nonionina), being an extension of the slit-like 

 aperture of Truncatulina lobatula in accordance with the in- 

 creased width of the chamber on the side which is undeveloped 

 in the latter flattened form. 



In the texture of shell, sunken umbilici, and almost sym- 

 metrically nautiloid form, this shell is an Anomalina, D'Orb. 



The specimen figured (figs. 15, 16) is the most symmetrical 

 of the individuals collected ; others approach more neai^ly to the 

 common Truncatulina. 



This is a very common form in the Norway dredgings ; being 

 comparatively numerous at 30, 40, 70-100, and 160 fathoms. 

 Elsewhere we have only found it in two deposits of the French 

 Tertiaries ; and there it appears to be of great rarity, though 

 even larger in size than the Norway specimens. 



* Serpula concamerata, Montagu; Lobatula concameratu, Fleming; 

 Planorbulina nitida and P. Mediterranensis, D'Orb. Ann. Sc. N. vii. p. 280. 



t Solclani, Testae, et Zoopli. pi. "i^-^'-i. 



X Acei-vulina, a genus instituted by Schultze (Organ. Polyth. &c.), but 

 to be taken in a larger sense than intended by that author, appears to form 

 a very typical group of species which, after develo])ing a certain number of 

 chambers as Rosalince, become more or less cyclical in their growth ; each 

 chamber developing new segments from one, two, or three funnel-shaped 

 apertures on its periphery. Truncatulina may be said to be an Acervulina 

 arrested at its Rosaline stage of growth. 



§ For the sake of convenience we retain the subgeneric names Truncatu- 

 lina and Anomalina instead of the more comprehensive term Acervulina. 



