108 GOES, RETICULARIAN RHIZOPODA OF THE CARIBBEAN SEA. 



In Microgeology by EHHENBEKG t. 35, B, fig. 7 there is represented a young 

 form called Spiropleurites nebulosus, which probably belongs to this species. From 

 Discorb. valvulata it differs only in closer and finer poration, not yellowish shell and 

 its pigmy size. 



Fig. 266: spire-side. 



Fig. 267: side-view; 268: apertural side. 



Syn. Bosalina Berthelotiana D'ORB., 1844, Hist, iles Canaries for., p. 135, t. 1, figg. 28 30. 



Discorbina Bertheloti BRADY, 1864, Rhizop. Shetl.; Trans. Lin. Soc. 24, p. 469, t. 48, fig. 10. 

 Parisiensis var. Berthelotiana PAKK. et JONES, 1865, North. Atl. and Arct. Oc. : Phil. 



Trans. 155. 1, p. 387, t. 16, figg. 26 27. 

 pRosalina concava Ess., 1854, Kreide. Ostalpen; Wien. Ak. Dkschr. 7, p. 70, t. 26, fig. 3. 



Discorbina vesicularis LMK. var. elegans D'ORB. 



Tab. VIII, figg. 269271. 



On the authority of Messrs PARKER and JONES we consider this form as identical 

 with Rosalina cornplanata D'ORB. (For. Bass. tert. Vienne p. 176, t. 10, figg. 13 15) 

 notwithstanding this, as also Ros. complanata Rss. (Neue For. osterreich. tert. Beck.; 

 Wien. Akad. Dkschr. 1. 1, p. 373, t. 47, fig. 5) has its spire less invested by the last 

 convolution. Our form is remarkable for the great symmetry of both its sides, which 

 are hardly distinguishable from each another; both being provided with a deep and 

 narrow umbilicus. The aperturale fissure is very inconspicuous. The valve or astral 

 lobes are represented by 2 or 3 small scalelike outgrowths partly covering the open- 

 ing of the umbilicus; the shell surface is somewhat polished. 



Where is not for the yellowish tint of the shell-substance in transmitted light 

 and for the characteristic size and disposition of the pore-canals one would hardly be 

 able to recognize this form as a Discorbina, but would rather refer it to Planorbulina. 



It is not common in the chalk-ooze, and is always found in a pigmy state. 



Fig. 269: spire-side. 



Fig. 270: side-view. 



Fig. 271: apertural-side. 



Syn. Anomalina elegans D'ORB., 1826, Tabl. meth., Aun. Sc. Nat. 7, p. 282; Mod. N:o 42. 



Spirillina vivipara EHRENB. 



Tab. VII, fig. 272. 



The pores of this very simple rhizopode are variable in closeness of arrangement. 

 Fullgrown specimens have them pretty close and of the same size as Planorbulina Ungeriana. 

 Very small ones are not easily distinguishable from young Trochammin* iricertae. 



It is very common; particularly in the chalk-ooze, seldom attaining in diameter 

 more than 0,20 mm. 



