KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND. 19. N:0 4. 131 



Miliolina ringens Lmk. 



Tab. X, figg. 361—386. 



The form which usually occurs on our bottom is identical with Biloculina hul- 

 loides dOrb. with its more or less broad, often carinated and inelined shelf, produced 

 by the excess of the last chamber beyond the preceding. The modification with lobate 

 limb — Bil. caudata Bornem., Bil. appendiculata Rss. — are often met with, but such 

 trifling features are too accidental to entitle to any separate designation whatever. 

 Biloc. sphcera Brady or Bil. glohulus Bornem. is ordinarily distinguished by higher 

 lustre and absence of limb, the sutural mark being quite faint; the shell nearly glo- 

 bular and the last chamber much larger than and överlappning the preceding one. 

 It is found associated with the typical form. 



Triloculina enoplostoma Rss. from the »Septarian-clay at Berlin, is a »triloculine» 

 form, which also occurs on our bottora, but is very rare. Its glossy porcellaneous 

 lustre and the shape of its aperture betray its close kindred to Mil. ringens. Some of 

 d'Orbigny's Triloculince may also be referred to this variety, as Triloc. Schreibersiana, 

 austriaca d'Obb. etc. also Triloc. circularis Bornem.; Triloc. valvularis Rss. From the 

 Atlantic ocean off the Azores Prof. Smitt and Ljungman brought liorae in 1868 an 

 extensive series of highly developed Miliolina ringens, elucidating the indistinct demar- 

 cation between it and Mil. seminulum. Some delineations of a few examples from this 

 valuable collection will illustrate this gradational transition- 



The form with tubulated round aperture recorded by Lamarck as Miliolit. ringens 

 and by Costa as Biloc. tubulosn has not been met with on our bottora. But in deep 

 water in the Atlantic it seeras to be common. 



The form )icontrariay> n'ORB. has not occurred. 



The typical form is sometimes finely striate — figg. 370 — 371. A handsome 

 costulate triloculine form is sometimes met with on our bottom, figg. 384 — 385. 



Figg. 361 — 362: the typical Mil. ringens, from chalk-bottom; the limb being thick 

 and uneven with folds. 



Figg. 363 — 365: oblong, cyclostome form {Biloc. tuhulosa Costa); from the At- 

 lantic off the Azores, 790 fathoms. Smitt and Ljungman. 



Figg. 366 — 367: depressed form {Bil. carinata, depressa d'Orb.) with nearly tu- 

 bular mouth; from the same locality as the preceding, 550 fathoms. 



Figg. 368 — 369: the spheroidal variety; the last chamber being much larger than 

 the preceding; from the chalk-bottom. 



Figg. 370 — 371: finely striate form; from the Atlantic, 790 fathoms, Smith and 

 'Ljungman. 



Figg. 372 — 373: triloculine variety, from the coralline-gravel off the Virgin Islands. 



Figg. 374 — 375: irregular, triloculine form of high development, from the Atlantic, 

 off the Azores, 600 fathoms, Smitt and L.tungman. 



Figg. 376 — 378: quadriloculine. tubulated form, from the same place. Smitt and 

 Ljungman. 



